Semiconductor device and method of manufacturing same

ABSTRACT

To provide a semiconductor device having a nonvolatile memory improved in characteristics. In the semiconductor device, a nonvolatile memory has a high-k insulating film (high dielectric constant film) between a control gate electrode portion and a memory gate electrode portion and a transistor of a peripheral circuit region has a high-k/metal configuration. The high-k insulating film arranged between the control gate electrode portion and the memory gate electrode portion relaxes an electric field intensity at the end portion (corner portion) of the memory gate electrode portion on the side of the control gate electrode portion. This results in reduction in uneven distribution of charges in a charge accumulation portion (silicon nitride film) and improvement in erase accuracy.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2013-243953 filed onNov. 26, 2013 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a semiconductor device and a method ofmanufacturing the semiconductor device and is suited for use in, forexample, a semiconductor device having a nonvolatile memory cell and amethod of manufacturing the semiconductor device.

Semiconductor devices having a memory cell region having therein, forexample, a memory cell of a nonvolatile memory formed on a semiconductorsubstrate and a peripheral circuit region having therein a peripheralcircuit comprised of, for example, a MISFET (metal insulatorsemiconductor field effect transistor) and formed on the semiconductorsubstrate have been used widely.

As the nonvolatile memory, a memory cell comprised of a split gate cellusing a MONOS (metal-oxide-nitride-oxide semiconductor) film issometimes used. This memory cell is comprised of two MISFETs, that is, acontrol transistor having a control gate electrode and a memorytransistor having a memory gate electrode. When both a memory cell ofsuch a nonvolatile memory and a MISFET configuring a peripheral circuitare loaded together on a semiconductor substrate, gate electrodes areformed in the respective regions.

For example, Patent Document 1 (Japanese Unexamined Patent ApplicationPublication No. 2011-49282) discloses a method of manufacturing asemiconductor device including forming a MISFET from a high-k film and ametal gate electrode through a damascene process.

Patent Document 2 (Japanese Unexamined Patent Application PublicationNo. 2011-103332) and Patent Document 3 (Japanese Unexamined PatentApplication Publication No. 2010-108976) disclose a semiconductor devicehaving a nonvolatile memory and a MISFET formed in a peripheral circuitregion. According to them, a high dielectric constant film is used as agate insulating film of the MISFET.

Patent Document 4 (Japanese Unexamined Patent Application PublicationNo. 2010-87252) discloses a split gate transistor having a highdielectric constant film as a gate insulating film below a control gateelectrode.

Patent Document 5 (Japanese Unexamined Patent Application PublicationNo. 2009-59927) discloses a method of manufacturing a nonvolatilesemiconductor memory device including forming a memory gate electrode onthe sidewall of a dummy gate and then removing the dummy gate to form acontrol gate electrode.

Patent Document 6 (Japanese Unexamined Patent Application PublicationNo. 2012-248652) discloses a split gate nonvolatile memory having amemory gate electrode made of a stacked film of a metal film and asilicon film thereon.

PATENT DOCUMENTS [Patent Document 1] Japanese Unexamined PatentApplication Publication No. 2011-49282 [Patent Document 2] JapaneseUnexamined Patent Application Publication No. 2011-103332 [PatentDocument 3] Japanese Unexamined Patent Application Publication No.2010-108976 [Patent Document 4] Japanese Unexamined Patent ApplicationPublication No. 2010-87252 [Patent Document 5] Japanese UnexaminedPatent Application Publication No. 2009-59927 [Patent Document 6]Japanese Unexamined Patent Application Publication No. 2012-248652SUMMARY

A memory cell of a nonvolatile memory or the like and an MISFETconfiguring a peripheral circuit are sometimes loaded on the samesemiconductor substrate.

As a gate insulating film of this MISFET, for example, a high dielectricconstant film, so-called high-k film, having a specific dielectricconstant higher than that of a silicon nitride film is sometimes usedand as a gate electrode of the MISFET, a so-called metal gate electrodeis sometimes used.

A semiconductor device having both such a MISFET and a memory cellrequires various investigations for finding manufacturing steps suitedfor it. In addition, the memory cell is sometimes desired to have ahigh-k film or a metal gate electrode from the standpoint ofminiaturization or reduction in power consumption. It is thereforenecessary to investigate the configuration of them or manufacturingsteps of the device based on the characteristics of the memory cell andMISFET to be loaded together.

The other problems and novel features will be apparent from thedescription herein and accompanying drawings.

The outline of typical embodiments, among the embodiments disclosedherein, will next be described briefly.

A semiconductor device according to one embodiment disclosed herein hasa first insulating film formed between a first gate electrode portionand a semiconductor substrate and a second insulating film formedbetween a second gate electrode portion and the semiconductor substrateand between the first gate electrode portion and the second gateelectrode portion and having a charge accumulation portion in the film.The first insulating film is formed between the first gate electrodeportion and the semiconductor substrate and between the first gateelectrode portion and the second gate electrode portion and has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. The first gate electrode portion and thefirst insulating film have therebetween a metal compound film.

A method of manufacturing a semiconductor device according to oneembodiment disclosed herein includes: forming a first conductive film ina first region of a semiconductor substrate via a first insulating film,successively forming a second insulating film and a second conductivefilm on the upper surface and side surface of the first conductive filmand in a second region adjacent to the first region, and etching thesecond insulating film and the second conductive film to leave thesecond conductive film in the second region via the second insulatingfilm. The second insulating film has a high dielectric constant filmhaving a dielectric constant higher than that of a silicon nitride film.

The semiconductor device shown in the typical embodiment disclosedherein can have improved characteristics.

The method of manufacturing a semiconductor device shown in the typicalembodiment disclosed herein can provide a semiconductor device havinggood characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a semiconductor device of FirstEmbodiment;

FIG. 2 is a cross-sectional view showing the semiconductor device ofFirst Embodiment;

FIG. 3 is a cross-sectional view showing the semiconductor device ofFirst Embodiment;

FIG. 4 is a plan view showing a memory array of the semiconductor deviceof First Embodiment;

FIG. 5 is a circuit diagram showing the memory array of thesemiconductor device of First Embodiment;

FIG. 6 is a block diagram showing a configuration example of thesemiconductor device of First Embodiment;

FIG. 7 is a cross-sectional view showing the semiconductor device ofFirst Embodiment;

FIG. 8 is a chart showing a flow of an erase operation from the start tothe end thereof;

FIG. 9 is a chart showing a flow of a write operation from the start tothe end thereof;

FIG. 10 shows a first example of an erase pulse;

FIG. 11 shows a second example of an erase pulse;

FIG. 12 shows a third example of an erase pulse;

FIG. 13 shows a first example of a write pulse;

FIG. 14 shows a second example of a write pulse;

FIG. 15 is a flow chart showing a manufacturing step of thesemiconductor device of First Embodiment;

FIG. 16 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment;

FIG. 17 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment;

FIG. 18 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 16;

FIG. 19 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 17;

FIG. 20 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 18;

FIG. 21 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 19;

FIG. 22 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 20;

FIG. 23 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 21;

FIG. 24 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 22;

FIG. 25 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 23;

FIG. 26 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 24;

FIG. 27 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 25;

FIG. 28 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 26;

FIG. 29 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 27;

FIG. 30 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 28;

FIG. 31 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 29;

FIG. 32 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 30;

FIG. 33 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 31;

FIG. 34 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 32;

FIG. 35 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 33;

FIG. 36 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 34;

FIG. 37 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 35;

FIG. 38 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 36;

FIG. 39 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 37;

FIG. 40 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 38;

FIG. 41 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 39;

FIG. 42 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 40;

FIG. 43 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 41;

FIG. 44 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 42;

FIG. 45 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 43;

FIG. 46 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 44;

FIG. 47 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 45;

FIG. 48 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 46;

FIG. 49 is a cross-sectional view showing a manufacturing step of thesemiconductor device of First Embodiment following that of FIG. 47;

FIG. 50 is a cross-sectional view showing a semiconductor device ofSecond Embodiment;

FIG. 51 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Second Embodiment;

FIG. 52 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Second Embodiment following that of FIG. 51;

FIG. 53 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Second Embodiment following that of FIG. 52;

FIG. 54 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Second Embodiment following that of FIG. 53;

FIG. 55 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Second Embodiment following that of FIG. 54;

FIG. 56 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Second Embodiment following that of FIG. 55;

FIG. 57 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Second Embodiment following that of FIG. 56;

FIG. 58 is a cross-sectional view showing a semiconductor device ofThird Embodiment;

FIG. 59 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Third Embodiment;

FIG. 60 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Third Embodiment following that of FIG. 59;

FIG. 61 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Third Embodiment following that of FIG. 60;

FIG. 62 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Third Embodiment following that of FIG. 61;

FIG. 63 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Third Embodiment following that of FIG. 62;

FIG. 64 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Third Embodiment following that of FIG. 63;

FIG. 65 is a cross-sectional view showing a semiconductor device ofFourth Embodiment;

FIG. 66 is a cross-sectional view showing a semiconductor device ofFifth Embodiment;

FIG. 67 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment;

FIG. 68 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 67;

FIG. 69 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 68;

FIG. 70 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 69;

FIG. 71 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 70;

FIG. 72 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 71;

FIG. 73 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 72;

FIG. 74 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 73;

FIG. 75 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 74;

FIG. 76 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 75;

FIG. 77 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 76;

FIG. 78 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Fifth Embodiment following that of FIG. 77;

FIG. 79 is a cross-sectional view showing a semiconductor device ofSixth Embodiment;

FIG. 80 is a cross-sectional view showing the semiconductor device ofSixth Embodiment;

FIG. 81 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment;

FIG. 82 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment;

FIG. 83 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 81;

FIG. 84 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 82;

FIG. 85 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 83;

FIG. 86 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 84;

FIG. 87 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 85;

FIG. 88 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 86;

FIG. 89 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 87;

FIG. 90 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 88;

FIG. 91 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 89;

FIG. 92 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 90;

FIG. 93 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 91;

FIG. 94 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 92;

FIG. 95 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 93;

FIG. 96 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 94;

FIG. 97 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 95;

FIG. 98 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Sixth Embodiment following that of FIG. 96;

FIG. 99 is a cross-sectional view showing a semiconductor device ofSeventh Embodiment;

FIG. 100 is a cross-sectional view showing a semiconductor device ofEighth Embodiment;

FIG. 101 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Eighth Embodiment;

FIG. 102 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Eighth Embodiment following that of FIG. 101;

FIG. 103 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Eighth Embodiment following that of FIG. 102;

FIG. 104 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Eighth Embodiment following that of FIG. 103;

FIG. 105 is a cross-sectional view showing a semiconductor device ofNinth Embodiment;

FIG. 106 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment;

FIG. 107 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment following that of FIG. 106;

FIG. 108 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment following that of FIG. 107;

FIG. 109 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment following that of FIG. 108;

FIG. 110 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment following that of FIG. 109;

FIG. 111 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment following that of FIG. 110;

FIG. 112 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment following that of FIG. 111;

FIG. 113 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment following that of FIG. 112;

FIG. 114 is a cross-sectional view showing a manufacturing step of thesemiconductor device of Ninth Embodiment following that of FIG. 113;

FIG. 115 is a cross-sectional view showing a semiconductor device ofTenth Embodiment;

FIG. 116 is a cross-sectional view showing a configuration of one ofperipheral transistors of a semiconductor device of Eleventh Embodiment;and

FIG. 117 is a cross-sectional view showing the configuration of a memorycell of a semiconductor device of Twelfth Embodiment.

DETAILED DESCRIPTION

In the following embodiments, a description may be made after divided ina plurality of sections or embodiments if necessary for the sake ofconvenience. These sections or embodiments are not independent from eachother unless otherwise particularly specified, but one of them may be amodification example, application example, detailed description,complementary description, or the like of a part or whole of the otherone. In the following embodiments, when a reference is made to thenumber of elements (including the number, value, amount, range, or thelike), the number is not limited to a specific number but may be more orless than the specific number, unless otherwise particularly specifiedor principally apparent that the number is limited to the specificnumber.

Further, in the following embodiments, the constituent component(including component step or the like) is not always essential unlessotherwise particularly specified or principally apparent that it isessential. Similarly, in the following embodiments, when a reference ismade to the shape, positional relationship, or the like of theconstituent component, that substantially approximate or analogous to itis also embraced unless otherwise particularly specified or principallyapparent that it is not. This also applies to the above-mentioned number(including the number, value, amount, range, or the like).

Embodiments will hereinafter be described in detail based on drawings.In all the drawings for describing the embodiments, members having thesame function will be identified by the same or like reference numeralsand overlapping descriptions will be omitted. When there is a pluralityof members (sites) similar to each other, a symbol may be added to thereference numeral to show an individual or specific site. In thefollowing embodiments, a description on the same or similar portion isnot repeated in principle unless otherwise particularly necessary.

In the drawings to be used in the following embodiments, even across-sectional view is sometimes not hatched to facilitateunderstanding of it or even a plan view may be hatched to facilitateunderstanding of it.

In the cross-sectional view and plan view, the dimensions of each sitedo not correspond to those of an actual device. To facilitateunderstanding of them, the dimensions of a particular site may beenlarged relatively. Even when a cross-sectional view and a plan viewcorrespond to each other, the dimensions of a particular site may beenlarged relatively to facilitate understanding of the drawing.

First Embodiment

The structure of a semiconductor device of the present embodiment willhereinafter be described referring to some drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.The transistor described herein is also called “MISFET” (metal insulatorsemiconductor field effect transistor).

(Description on the Structure of a Memory Cell)

FIGS. 1 to 3 are cross-sectional views showing the semiconductor deviceof the present embodiment. FIG. 4 is a plan view showing a memory arrayof the semiconductor device of the present embodiment. For example, FIG.1 corresponds to the A-A cross-section of FIG. 4; FIG. 2 corresponds tothe B-B cross-section and the C-C cross-section of FIG. 4; and FIG. 3corresponds to the D-D cross-section of FIG. 4. FIG. 5 is a circuitdiagram showing the memory array of the semiconductor device of thepresent embodiment. FIG. 6 is a block diagram showing a configurationexample of the semiconductor device of the present embodiment.

As shown in FIGS. 1 to 3, the memory cell (element) is comprised of acontrol transistor having a control gate electrode portion CG and amemory transistor having a memory gate electrode portion MG.

More specifically, the memory cell has a control gate electrode portionCG arranged over a semiconductor substrate 100 (p well PW) and a memorygate electrode portion MG arranged over the semiconductor substrate 100(p well PW) and adjacent to the control gate electrode portion CG. Forexample, the control gate electrode portion CG and the memory gateelectrode portion MG are each made of a silicon film. The silicon filmhas thereover a metal silicide film SIL.

The memory cell further has an insulating film and a metal compound filmarranged between the control gate electrode portion CG and thesemiconductor substrate 100 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. As FIG. 1 shows, the memory cell has asilicon oxide film 113 and a high-k insulating film (high dielectricconstant film) 114 as the insulating-film. Further, the high-kinsulating film 114 and the control gate electrode portion CG havetherebetween a titanium nitride film 115 as the metal compound film(barrier film).

The high-k insulating film (high dielectric constant film) 114 liesbetween the control gate electrode portion CG and the semiconductorsubstrate 100 (p well PW) and between the control gate electrode portionCG and the memory gate electrode portion MG.

The titanium nitride film 115 (metal compound film) lies between thecontrol gate electrode portion CG and the semiconductor substrate 100 (pwell PW) and between the control gate electrode portion CG and thememory gate electrode portion MG.

The memory cell further has an insulating film ONO (106, 107, 108)arranged between the memory gate electrode portion MG and thesemiconductor substrate 100 (p well PW). The insulating film ONO iscomprised of, for example, a silicon oxide film 106, a silicon nitridefilm 107 thereon, and a silicon oxynitride film 108 thereon. The siliconnitride film 107 will serve as a charge accumulation portion.

The insulating film ONO (106, 107, 108) are provided between the memorygate electrode portion MG and the semiconductor substrate 100(p well PW)and between the control gate electrode portion CG and the memory gateelectrode portion MG.

This means that the control gate electrode portion CG and the memorygate electrode portion MG have therebetween the insulating film ONO(106, 107, 108), the high-k insulating film (high dielectric constantfilm) 114, and the metal compound film (titanium nitride film 115) whichare arranged in order of mention from the side of the memory gateelectrode portion MG.

The memory cell further has a source region MS and a drain region MDformed in the p well PW of the semiconductor substrate 100. The memorygate electrode portion MG and the control gate electrode portion CG has,on the sidewall portion of the synthesis pattern thereof, a sidewallfilm (sidewall insulating film, sidewall spacer) SW made of aninsulating film.

The source region MS is comprised of an n⁺ type semiconductor region 119b and an n⁻ type semiconductor region 119 a. The n⁻ type semiconductorregion 119 a is a region formed in self alignment with the sidewall ofthe control gate electrode portion CG. The n⁺ type semiconductor region119 b is a region formed in self alignment with the side surface of thesidewall film SW on the side of the control gate electrode portion CGand has a junction depth and an impurity concentration greater thanthose of the n⁻ type semiconductor region 119 a. Such a source electrode(or drain electrode) comprised of a lightly doped semiconductor regionand a heavily doped semiconductor region is called a source electrode(or drain electrode) with an LDD (lightly doped drain) structure.

The drain region MD is comprised of an n⁺ type semiconductor region 111b and an n⁻ type semiconductor region 111 a. The n⁻ type semiconductorregion 111 a is a region formed in self alignment with the sidewall ofthe memory gate electrode portion MG. The n⁺ type semiconductor region111 b is a region formed in self alignment with the side surface of thesidewall film SW on the side of the memory gate electrode portion MG andhas a junction depth and an impurity concentration greater than those ofthe n⁻ type semiconductor region 111 a.

In the present specification, the source region MS and the drain regionMD are defined based on the magnitude of voltage to be applied thereto.A semiconductor region to which a high voltage is applied upon writeoperation which will be described later will hereinafter be called“drain region MD” and a semiconductor region to which a low voltage isapplied upon write operation will hereinafter be called “source regionMS” consistently.

The control gate electrode portion CG, the memory gate electrode portionMG, the source region MS (n⁺ type semiconductor region 119 b), and thedrain region MD (n⁺ type semiconductor region 111 b) have thereover ametal silicide film SIL.

The memory cell has thereon a silicon oxide film 121 as an interlayerinsulating film and this silicon oxide film 121 has thereon a siliconoxide film 124 as an interlayer insulating film. This silicon oxide film124 has thereon a wiring 125 and the like.

Two memory cells shown in FIG. 1 are arranged substantiallysymmetrically with the drain region MD therebetween. As will bedescribed later, a plurality of memory cells is arranged in the memorycell region MA. For example, a memory cell on the left side in thememory cell region MA shown in FIG. 1 has, on a further left sidethereof, another memory cell (not illustrated) having the source regionMS in common.

A region between the control gate electrode portions arranged with thissource region therebetween will hereinafter be called “region CCA”. Aregion between memory gate electrode portions MG arranged with the drainregion MD therebetween will hereinafter be called “region MMA”. In FIG.1, the region MMA has, on both sides thereof, the regions CCA. Thisregion CCA includes the formation regions of the high-k insulating film(high dielectric constant film) 114 and the metal compound film(titanium nitride film 115) arranged along the sidewall of the controlgate electrode portion CG. The region MMA, on the other hand, includesthe formation region of the insulating film ONO (106, 107, 108) arrangedalong the sidewall of the memory gate electrode portion MG.

As described above, memory cells are arranged in a horizontal direction(gate length direction) in FIG. 1 so that the drain region MD and thesource region, each shared by two adjacent memory cells, are arrangedalternately and they configure a memory cell array. In addition, thereis a plurality of memory cell arrays arranged in a direction (gate widthdirection) perpendicular to the paper plane of FIG. 1. A plurality ofmemory cells therefore lie in array form. The memory cell array willhereinafter be described referring to FIGS. 4 to 6.

(Memory Array)

As shown in FIG. 4, the control gate electrode portions CG (CG1, CG2,CG3, CG4) and the memory gate electrode portions MG (MG1, MG2, MG3, MG4)of the memory cell extend in direction Y (direction crossing with theA-A cross-sectional portion, a longitudinal direction of the paperplane).

A plurality of active regions (hatched portions) is provided in a lineshape extending in direction X and lines extending in direction X arecoupled to each other by a coupling portion extending in direction Y.These active regions are defined by element isolation regions 103 andare exposed regions of the p well PW.

The control gate electrode portions CG and also the memory gateelectrode portions MG are symmetrical about the above-mentioned couplingportion. The active regions on the side of the control gate electrodeportions CG (CG1, CG2, CG3, CG4) have thereover contact portions.Wirings (ML1, ML2, ML3, ML4) extend in direction X so as to couple thecontact portions arranged in direction X. The coupling portions havetherebetween a drain region MD. This region (between the couplingportions) will be a drain line (Drain 1, Drain 2) which will bedescribed later. The contact portions have therebelow source regions MS.The wirings (ML1, ML2, ML3, ML4) will be source lines (Source 1, Source2, Source 3, Source 4) which will be described later.

As shown in FIG. 5, the memory cells (memory transistors, controltransistors) are arranged in array form at intersections between Drain 1and Drain 2 and Source 1, Source 2, Source 3, and Source 4.

As shown in FIG. 6, the memory cell array 9 is in a memory portion B.For example, this memory portion B and a logic portion A configure asemiconductor device C of the present embodiment.

The memory portion B is comprised of, for example, a control circuit 1,an input/output circuit 2, an address buffer 3, a row decoder 4, acolumn decoder 5, a verify sense amplifier circuit 6, a high-speed readsense amplifier circuit 7, a write circuit 8, a memory cell array 9, anda power supply circuit 10. The control circuit 1 controls a controlsignal temporarily stored therein after inputted from the logic portionA. The control circuit 1 also controls the potential of the control gateelectrode portion CG and the memory gate electrode portion MG of thememory cell in the memory cell array 9. Various data such as data to beread from the memory array 9 or written to the memory array 9 or programdata is inputted/outputted to and from the input/output circuit 2. Theaddress buffer 3 temporarily stores therein an address inputted from thelogic portion A. The row decoder 4 and the column decoder 5 are eachcoupled to the address buffer 3. The row decoder 4 decodes based on arow address outputted from the address buffer 3 and the column decoder 5decodes based on a column address outputted from the address buffer 3.The verify sense amplifier circuit 6 is a sense amplifier for aread/write verify operation. The high-speed read sense amplifier circuit7 is a read sense amplifier used upon data reading. The write circuit 8latches write data inputted via the input/output circuit 2 and controlsdata writing. The power supply circuit 10 is comprised of a voltagegeneration circuit for generating various voltages to be used upon datawriting, data erasing, data verifying or the like, a current trimmingcircuit 11 for generating and supplying an arbitrary voltage value tothe write circuit, and the like.

The configurations shown in FIGS. 4 to 6 are only examples and theconfiguration of the semiconductor device of the present embodiment isnot limited to them.

(Description on Peripheral Transistor)

Various circuits provided around the memory cell array 9 are comprisedof an element such as peripheral transistor. FIG. 7 is a cross-sectionalview showing the semiconductor device of the present embodiment.

As shown in FIG. 7, the peripheral transistor has a gate electrodeportion GE arranged over the semiconductor substrate 100 (p well PW) anda source/drain region SD provided in the p well PW on both sides of thegate electrode portion GE. The gate electrode portion GE is comprised ofa metal electrode film 122 and a metal film 123 thereon. The peripheraltransistor further has an insulating film and a metal compound filmarranged between the gate electrode portion GE and the semiconductorsubstrate 100 (p well PW). The insulating film has a high dielectricconstant film having a dielectric constant higher than that of a siliconnitride film. As shown in FIG. 7, the peripheral transistor has, as theinsulating film, a silicon oxide film 113 and a high-k insulating film(high dielectric constant film) 114 and, as the metal compound film, atitanium nitride film 115 provided between the high-k insulating film114 and the gate electrode portion GE.

The gate electrode portion GE has, on the sidewall portion thereof, asidewall film SW made of an insulating film. The source/drain region SDis comprised of an n⁺ type semiconductor region 119 b and an n⁻ typesemiconductor region 119 a. The n⁻ type semiconductor region 119 a isformed in self alignment with the sidewall of the gate electrode portionGE. The n⁺ type semiconductor region 119 b is formed in self alignmentwith the side surface of the sidewall film SW and has a junction depthand an impurity concentration greater than those of the n⁻ typesemiconductor region 119 a. This source/drain region SD (n⁺ typesemiconductor region 119 b) has thereon a metal silicide film SIL.

The gate electrode portion GE of the peripheral transistor has, on bothsides thereof, a silicon oxide film 121 as an interlayer insulating filmand this silicon oxide film 121 has thereon a silicon oxide film 124 asan interlayer insulating film.

(Operation)

Next, one example of basic operations of the memory cell will bedescribed. Three operations, that is, (1) read operation, (2) eraseoperation, and (3) write operation will be described as the operationsof the memory cell. There are however various definitions of theseoperations and in particular, the erase operation and the writeoperation are sometimes defined conversely.

(1) Read Operation

For example, the channel below the control gate electrode portion CG isturned ON by applying a positive potential of about 1.2 V to the sourceregion MS on the side of the control gate electrode portion CG andapplying a positive potential of about 1.2 V to the control gateelectrode portion CG. By setting the memory gate electrode portion MG ata predetermined potential (meaning a middle potential between athreshold voltage in write state and a threshold voltage in erasestate), retained charge data can be read as a current. By setting themiddle potential between the threshold voltage in write state and thethreshold voltage in erase state at 0 V, boosting of a voltage to beapplied to the memory gate electrode portion MG in a power supplycircuit becomes unnecessary, making it possible to achieve high-speedreading.

(2) Erase Operation

For example, a voltage of 12 V is applied to the memory gate electrodeportion MG, a voltage of 0 V is applied to the control gate electrodeportion CG, a voltage of 0 V is applied to the drain region MD on theside of the memory gate electrode portion MG, and a voltage of 0 V isapplied to the source region MS on the side of the control gateelectrode portion CG. Holes are injected into the silicon nitride film107 (charge accumulation portion) from the side of the memory gateelectrode portion MG through an FN tunneling phenomenon (FN tunnelingsystem) to achieve erasure (FN tunneling system). However, the sourceregion MS on the side of the control gate electrode portion CG may beelectrically opened or a potential of about 1 V may be applied to thecontrol gate electrode portion CG.

FIG. 8 is a chart showing a flow of an erase operation from the start tothe end thereof. As shown in FIG. 8, an erase pulse is applied and holesare injected into the silicon nitride film 107 to achieve erasure. Then,a verify operation is performed to find whether the memory cell hasreached a desired threshold voltage or not. When the memory cell doesnot reach the desired threshold voltage, a sequence of applying an erasepulse is repeated. When it has reached the desired threshold voltage,the erase operation is ended.

When the verify operation is performed after the first erase operation(N=1) and then, the erase operation is performed further (N>1), eraseconditions need not necessarily be the same as those for the first eraseconditions. FIG. 10 shows an example of the erase pulse. As shown inFIG. 10, the first erase operation (N=1) is performed by setting thememory gate electrode portion MG at 12 V, the control gate electrodeportion CG at 0 V, the drain region MD (Drain) at 0 V, the source regionMS (Source) at 0 V, and the p well PW (Well) at 0 V. The second orsubsequent erase operation (N>1) is then performed by setting the memorygate electrode portion MG at 14 V, the control gate electrode portion CGat 0 V, the drain region MD (Drain) at 0 V, the source region MS(Source) at 0 V, and the p well PW (Well) at 0 V.

A second example of an erase pulse is shown in FIG. 11. As shown in FIG.11, a negative potential may be applied to the p well PW (Well). Asshown in FIG. 11, the first erase operation (N=1) is performed bysetting the memory gate electrode portion MG at 11 V, the control gateelectrode portion CG at 0 V, the drain region MD (Drain) at 0 V, thesource region MS (Source) at 0 V, and the p well PW (Well) at −1 V. Thesecond or subsequent erase operation (N>1) is then performed by settingthe memory gate electrode portion MG at 13 V, the control gate electrodeportion CG at 0 V, the drain region MD (Drain) at 0 V, the source regionMS (Source) at 0 V, and the p well PW (Well) at −1 V. In this case, apotential difference between the memory gate electrode portion MG andthe p well PW (Well) becomes greater than a potential difference betweenthe memory gate electrode portion MG and the control gate electrodeportion CG. This facilitates injection of holes into the silicon nitridefilm 107 below the memory gate electrode portion MG. As a result,electrons in the silicon nitride film 107 can be erased efficiently.

The erase operation may be achieved by generating hot holes on the sideof the substrate (Well) through band-band tunneling and injecting theminto the silicon nitride film 107 (BTBT system). A third example of anerase pulse is shown in FIG. 12. As shown in FIG. 12, the first eraseoperation (N=1) is performed by setting the memory gate electrodeportion MG at −6 V, the control gate electrode portion CG at 0 V, thedrain region MD (Drain) in an open state, the source region MS (Source)at 6 V, and the p well PW (Well) at 0 V. The second or subsequent eraseoperation (N>1) is then performed by setting the memory gate electrodeportion MG at −7 V, the control gate electrode portion CG at 0 V, thedrain region MD (Drain) in an open state, the source region MS (Source)at 7 V, and the p well PW (Well) at 0 V. In this case, the thresholdvoltage of the memory cell can be set lower, making it possible toincrease a channel current and in addition, speed up the erase operationof the memory cell.

(3) Write Operation

For example, a voltage of 10.5 V is applied to the memory gate electrodeportion MG, a voltage of 0.9 V is applied to the control gate electrodeportion CG, a voltage of 4.6 V is applied to the drain region MD on theside of the memory gate electrode portion MG, and a potential lower thanthat applied to the drain region, for example, 0.3 V is applied to thesource region MS on the side of the control gate electrode portion CG.As a result, concentrated injection of electrons is performed into anend portion of the memory gate electrode portion MG on the side of thecontrol gate electrode portion CG. This injection system is called anSSI (source side hot electron) injection system.

FIG. 9 is a chart showing a flow of a write operation from the start tothe end thereof. As shown in FIG. 9, a write operation is performed byapplying an SSI pulse to inject electrons into the silicon nitride film107. Then, a verify operation is performed to verify whether the memorycell has reached a desired threshold voltage or not. When the memorycell has not reached the desired threshold voltage, a sequence ofapplying an SSI pulse is repeated. When the memory cell has reached thedesired threshold voltage, the write operation is ended.

When the verify operation is performed after the first write operation(N=1) and then a write operation is performed further (N>1), writeconditions need not necessarily be the same as those for the first writeconditions. FIG. 13 shows a first example of a write pulse. As shown inFIG. 13, the first write operation (N=1) is performed by setting thememory gate electrode portion MG at 10 V, the control gate electrodeportion CG at 0.9 V, the drain region MD (Drain) at 4.5 V, the sourceregion MS (Source) at 0.3 V, and the p well PW (Well) at 0 V. The secondor subsequent write operation (N>1) is then performed by setting thememory gate electrode portion MG at 11 V, the control gate electrodeportion CG at 0.9 V, the drain region MD (Drain) at 4.9 V, the sourceregion MS (Source) at 0.3 V, and the p well PW (Well) at 0 V.

A second example of a write pulse is shown in FIG. 14. As shown in FIG.14, a negative potential may be applied to the p well PW (Well). Asshown in FIG. 14, the first erase operation (N=1) is performed bysetting the memory gate electrode portion MG at 10 V, the control gateelectrode portion CG at 1.5 V, the drain region MD (Drain) at 4.5 V, thesource region MS (Source) at 0.3 V, and the p well PW (Well) at −1 V.The second or subsequent write operation is (N>1) then performed bysetting the memory gate electrode portion MG at 11 V, the control gateelectrode portion CG at 1.5 V, the drain region MD (Drain) at 4.9 V, thesource region MS (Source) at 0.3 V, and the p well PW (Well) at −1 V. Inthis case, a potential difference between the drain region MD and the pwell PW (Well) or a potential difference between the memory gateelectrode portion MG and the p well PW (Well) can be made greater sothat high-speed write operation can be achieved.

In the present embodiment, since the control gate electrode portion CGand the memory gate electrode portion MG have therebetween the high-kinsulating film (high dielectric constant film) 114, an electric fieldintensity at the end portion (corner portion) of the memory gateelectrode portion MG on the side of the control gate electrode portionCG is relaxed upon erasing. This makes it possible to reduce unevendistribution of charges in the charge accumulation portion (siliconnitride film 107) and thereby improve the erase accuracy.

In particular, an electric field becomes larger at the end portion(corner portion) of the memory gate electrode portion MG on the side ofthe control gate electrode portion CG when erasing is performed throughthe above-mentioned FN tunnel system compared with erasing through theBTBT system. Concentrated injection of many holes occurs at this endportion. As a result, deterioration in erase accuracy may presumablyoccur due to variation in the distribution of charges (holes, electrons)in the charge accumulation portion (silicon nitride film 107).

In the present embodiment, on the other hand, the control gate electrodeportion CG and the memory gate electrode portion MG have therebetweenthe high-k insulating film (high dielectric constant film) 114 so thatan electric field intensity at the end portion (corner portion) of thememory gate electrode portion MG on the side of the control gateelectrode portion CG is relaxed upon erase operation, resulting inimprovement in erase accuracy.

Further, in the present embodiment, the control gate electrode portionCG and the memory gate electrode portion MG have therebetween theinsulating film ONO (106, 107, 108), the high-k insulating film 114, andthe metal compound film (titanium nitride film 115) are arrangedsuccessively from the side of the memory gate electrode portion MG sothat an electric field intensity at the end portion (corner portion) ofthe memory gate electrode portion MG on the side of the control gateelectrode is relaxed upon erasing. This leads to improvement in eraseaccuracy.

In the present embodiment, an n-MOS type memory cell has been describedin detail, but a p-MOS type memory cell, if having the configuration ofthe present embodiment, can produce an advantage similar to that of then-MOS type memory cell. Also as the peripheral transistor, an n-MOS typetransistor is shown as an example, but a p-MOS type transistor may beused as the peripheral transistor or both an n-MOS type transistor and ap-MOS type transistor may be formed in the peripheral circuit region PA.

[Description on Manufacturing Method]

Next, referring to FIGS. 15 to 49, a method of manufacturing thesemiconductor device of the present embodiment will be described. FIG.15 is a flow chart showing manufacturing steps of the semiconductordevice of the present embodiment and FIGS. 16 to 49 are cross-sectionalviews showing the manufacturing steps of the semiconductor device of thepresent embodiment.

A step of forming a memory cell in the memory cell region MA and aperipheral transistor in the peripheral circuit region PA will next bedescribed referring to these drawings.

As shown in FIG. 15, the manufacturing flow of the semiconductor deviceincludes a step of forming an element isolation region (ST1), a step offorming a well (ST2), a step of forming a memory gate electrode portionand a charge accumulation film (ST3), a step of forming a control gateelectrode portion and a peripheral transistor (ST4), and a step offorming a contact (plug) and a wiring (ST5). These steps willhereinafter be described specifically.

First, as shown in FIGS. 16 and 17, an element isolation region 103 isformed in the main surface of a semiconductor substrate 100. Describedspecifically, as the semiconductor substrate 100, a semiconductorsubstrate, for example, having a specific resistance of from about 1 to10 Ωcm and made of p type single crystal silicon is provided first.Next, the semiconductor substrate 100 is thermally oxidized to form asilicon oxide film 101 of about 10 nm thick. Then, a silicon nitridefilm 102 of about 50 nm thick is deposited on the silicon oxide film 101by CVD (chemical vapor deposition) or the like. Next, the silicon oxidefilm 101, the silicon nitride film 102, and the semiconductor substrate100 are etched using photolithography and dry etching to form an elementisolation trench of about 150 nm deep. A silicon oxide film is depositedon the silicon nitride film 102 and also in the element isolation trenchby CVD or the like, followed by removal of the silicon oxide filmoutside the element isolation trench by CMP (chemical mechanicalpolishing) or the like to fill the element isolation trench with theinsulating film such as silicon oxide film. Such an element isolationprocess is called STI (shallow trench isolation).

Next, as shown in FIGS. 18 and 19, a p well PW is formed in thesemiconductor substrate 100. First, the silicon nitride film 102 isremoved. Then, ion implantation of a p type impurity (for example, boron(B)) is performed while using the silicon oxide film 101 as a throughfilm to form a p well PW. Although FIGS. 18 and 19 show only the p wellPW formation region, an n well may formed in another region by ionimplantation of an n type impurity.

Next, as shown in FIGS. 20 and 21, a polysilicon film 105 is formed onthe semiconductor substrate 100. The polysilicon film 105 is a filmconfiguring a sidewall of the memory gate electrode portion MG when itis formed in sidewall shape. The sidewall may be made of anothermaterial film.

First, after removal of the silicon oxide film 101 by wet etching or thelike, a silicon oxide film 104 of about 2 nm thick is formed on thesemiconductor substrate 100 by thermal oxidation. Then, a polysiliconfilm 105 of about 120 nm thick is formed on the silicon oxide film 104and the element isolation region 103 by CVD or the like.

Next, as shown in FIGS. 22 and 23, an opening portion OA1 is formed inthe polysilicon film 105. This opening portion OA1 is formed by removingthe polysilicon film 105 and the underlying silicon oxide film 104 fromthe region MMA, for example, by photolithography and dry etching. Inother words, a stacked film of the polysilicon film 105 and the siliconoxide film 104 is left in the region CCA. At this time, the stacked filmof the polysilicon film 105 and the silicon oxide film 104 is left alsoin the peripheral circuit region PA. The opening portion OA1 has a widthof, for example, about 200 nm.

Next, as shown in FIGS. 24 to 27, an insulating film ONO (106, 107, 108)and a memory gate electrode portion MG are formed. First as shown inFIGS. 24 and 25, the insulating film ONO (106, 107, 108) is formed inthe opening portion OA1 and on the polysilicon film 105. For example, asilicon oxide film 106 is formed on the semiconductor substrate 100 bythermal oxidation and the silicon oxide film 106 thus formed has athickness of about 4 nm. The silicon oxide film 106 may be formed usingCVD or the like. Then, a silicon nitride film 107 of about 6 nm thick isdeposited on the silicon oxide film 106, for example, by CVD. Thissilicon nitride film 107 serves as a charge accumulation portion of thememory cell and becomes an intermediate layer configuring the insulatingfilm ONO. Then, a silicon oxynitride film 108 of about 8 nm thick isdeposited on the silicon nitride film 107 by CVD. In such a manner, theinsulating film ONO comprised of the silicon oxide film 106, the siliconnitride film 107, and the silicon oxynitride film 108 can be formed.

The insulating film ONO thus obtained functions as a gate insulatingfilm of a memory transistor and has a charge retention (chargeaccumulation) function. It has therefore a stacked structure of at leastthree layers and these layers are configured so that the potentialbarrier height of an inner layer (silicon nitride film 107) be smallerthan the potential barrier height of the outer layers (the silicon oxidefilm 106 and the silicon oxynitride film 108). In the presentembodiment, the silicon nitride film 107 is formed as a chargeaccumulation portion inside the insulating film ONO, but anotherinsulating film such as silicon oxynitride film, aluminum oxide film,hafnium oxide film, or tantalum oxide film may be used as the chargeaccumulation portion. The thickness of each of the films configuring theinsulating film ONO is not limited to the above-mentioned one and it canbe adjusted as needed, for example, according to the operation system ofthe resulting memory cell.

Next, a polysilicon film 109 of about 40 nm thick is deposited on theinsulating film ONO (106, 107, and 108) by CVD or the like (FIG. 24 andFIG. 25).

Next, as shown in FIGS. 26 and 27, a polysilicon film 109 in sidewallshape is formed on the sidewall portion of the opening portion OA1(polysilicon film 105).

For example, the polysilicon film 109 is etched back. In this etch backstep, the polysilicon film 109 of a predetermined thickness from thesurface thereof is removed by anisotropic etching. This etch back stepmakes it possible to leave the polysilicon film 109 in sidewall shape(in sidewall film shape) on the sidewall portion of the opening portionOA1 (polysilicon film 105) via the insulating film ONO. This polysiliconfilm 109 becomes a memory gate electrode portion MG. A memory gatelength (gate length of the memory gate electrode portion MG) isdetermined, depending on the deposition thickness of the polysiliconfilm 109. By adjusting the deposition thickness of the polysilicon film105 and the deposition thickness of the polysilicon film 109, the heightof the memory gate electrode portion MG can be adjusted. A dummy gateformation region may be provided in order to improve the processabilityof the memory gate. For example, the memory cell formed at the endportion of the memory array may presumably vary in characteristics. Forexample, variation in the dimensions of the polysilicon film 109 occurs,leading to variation in the characteristics of the memory cell. It istherefore possible to form a dummy gate formation region at the endportion of the memory array and use, as a dummy gate, the polysiliconfilm 109 formed at both end portions of the control gate electrodeportion CG, and thereby prevent it from contributing to the operation ofthe memory cell.

Next, as shown in FIGS. 28 and 29, a drain region MD and a silicon oxidefilm 112 are formed.

First, with the polysilicon film 105 and the polysilicon film 109 as amask, an n type impurity such as arsenic (As) or phosphorus (P) isimplanted into the bottom surface (p well PW) of the opening portion OA1to form an n⁻ type semiconductor region 111 a. This n⁻ typesemiconductor region 111 a is formed in self alignment with the sidewallof the polysilicon film 109. Next, a sidewall film (sidewall insulatingfilm) SW is formed on the sidewall portion of the polysilicon film 109.For example, a silicon oxide film is deposited in the opening portionOA1 and on the polysilicon films 105 and 109 by CVD or the like. Theresulting silicon oxide film of a predetermined thickness from thesurface thereof is removed by anisotropic dry etching to form a sidewallfilm SW on the sidewall portion of the polysilicon film 109. Then, withthe polysilicon films 105 and 109 and the sidewall film SW as a mask, ann type impurity such as arsenic (Ar) or phosphorus (P) is implanted intothe bottom surface (p well PW) of the opening portion OA1 to form an n⁺type semiconductor region 111 b. This n⁺ type semiconductor region 111 bis formed in self alignment with the sidewall film SW. The n⁺ typesemiconductor region 111 b has an impurity concentration and a junctiondepth greater than those of the n⁻ type semiconductor region 111 a. Thedrain region MD comprised of the n⁻ type semiconductor region 111 a andthe n⁺ type semiconductor region 111 b is thus formed by theabove-mentioned step.

Next, a silicon oxide film 112 is deposited in the opening portion OA1and on the polysilicon films 105 and 109. This silicon oxide film 112 ispreferably an SOG (spin on glass) film having a large wet etching ratebecause it will be removed in a later step.

Next, as shown in FIGS. 30 and 31, an upper portion of the silicon oxidefilm 112 is removed until the surface of the polysilicon film 105 isexposed. For example, the upper portion of the silicon oxide film 112 isremoved using a method such as CMP and wet etching until the surface ofthe polysilicon film 105 is exposed. By this step, the opening portionOA1 between the polysilicon films 109 is filled with the silicon oxidefilm 112. As a result, the polysilicon film 109 is covered with thesilicon oxide film 112 and the polysilicon film 105 of the region CCA isexposed in the memory cell region MA. In addition, the polysilicon film105 of the peripheral circuit region PA is exposed.

Next, as shown in FIGS. 32 and 33, the polysilicon film 105 is removedand a high-k insulating film 114 and the like are formed. First, thepolysilicon film 105 is removed and a silicon oxide film 113 of about 1nm thick is formed on the semiconductor substrate 100 (p well PW) of theregion CCA by thermal oxidation or the like. Next, a high-k insulatingfilm 114 is formed on the silicon oxide film 113 and the silicon oxidefilm 112. As the high-k insulating film 114, for example, an Hf oxidefilm can be used. For example, an Hf oxide film of about 5 nm thick isdeposited using CVD or the like. Next, a titanium nitride film 115 ofabout 10 nm thick is deposited on the high-k insulating film 114 by CVDor the like.

Next, a polysilicon film 116 of about 100 nm thick is deposited on thetitanium nitride film 115 by CVD or the like (FIG. 32 and FIG. 33).

Next, as shown in FIGS. 34 and 35, the polysilicon film 116 isplanarized by removing an upper portion thereof by CMP or the like. Atthis time, the polishing amount is controlled so that the surface heightof the polysilicon film 116 arranged on the semiconductor substrate 100(p well PW) via the stacked film of the silicon oxide film 113, thehigh-k insulating film 114, and the titanium nitride film 115 be about80 nm from the semiconductor substrate 100 (p well PW). By this step, inthe region MMA, the polysilicon film 109 and the silicon oxide film 112are exposed, while in the region CCA, the polysilicon film 116 isexposed. The polysilicon film 109 of the region MMA becomes a memorygate electrode portion MG.

Next, as shown in FIGS. 36 and 37, a silicon nitride film 117 isdeposited on the polysilicon films 116 and 109 and the silicon oxidefilm 112 by CVD or the like. Next, the silicon nitride film 117 is leftonly in the peripheral circuit region PA by photolithography and dryetching.

Next, as shown in FIGS. 38 and 39, a control gate electrode portion CGis formed in the memory cell region MA; a polysilicon film 116 forsubstitution of a gate electrode portion is formed in the peripheralcircuit region PA; and a source region MS of the memory cell and asource/drain region SD of the peripheral transistor are formed.

First, the polysilicon film 116 and the stacked film of the siliconoxide film 113, the high-k insulating film 114, and the titanium nitridefilm 115 are etched using photolithography and dry etching. By thisstep, a control gate electrode portion CG is formed in the memory cellregion MA. In the peripheral circuit region PA, the silicon nitride film117, the polysilicon film 116, and the stacked film of the silicon oxidefilm 113, the high-k insulating film 114, and the titanium nitride film115 are etched. By this step, the polysilicon film 116 for substitutionof a gate electrode portion is formed. The polysilicon film 116 forsubstitution of a gate electrode portion has thereon a remaining siliconnitride film 117.

By the above-mentioned etching, in the region CCA of the memory cellregion MA, the semiconductor substrate 100 (p well PW) on one side ofthe control gate electrode portion CG is exposed and in the peripheralcircuit region PA, the semiconductor substrate 100 (p well PW) on bothsides of the polysilicon film 116 is exposed.

Next, with the silicon oxide film 112, the control gate electrodeportion CG, and the polysilicon film 116 as a mask, an n type impuritysuch as arsenic (As) or phosphorus (P) is implanted into the exposedportion of the semiconductor substrate 100 (p well PW) to form an n⁻type semiconductor region 119 a. At this time, the n⁻ type semiconductorregion 119 a is formed in self alignment with the sidewall of thecontrol gate electrode portion CG or the polysilicon film 116.

Next, a sidewall film (sidewall insulating film) SW is formed on thesidewall portion of the control gate electrode portion CG and thepolysilicon film 116. A silicon oxide film 118 is deposited on thesemiconductor substrate 100 (p well PW) including the respective uppersurfaces of the silicon oxide film 112, the control gate electrodeportion CG, and the polysilicon film 116 by CVD or the like. Theresulting silicon oxide film 118 of a predetermined thickness from thesurface thereof is then removed by anisotropic dry etching to form asidewall film SW on the respective sidewall portions of the control gateelectrode portion CG and the polysilicon film 116.

Next, with the control gate electrode portion CG, the polysilicon film116, the sidewall film SW, and the like as a mask, an n type impuritysuch as arsenic (As) or phosphorus (P) is implanted into thesemiconductor substrate 100 (p well PW) to form an n⁺ type semiconductorregion 119 b. At this time, this n⁺ type semiconductor region 119 b isformed in self alignment with the sidewall film SW. This n⁺ typesemiconductor region 119 b has an impurity concentration and a junctiondepth greater than those of the n⁻ type semiconductor region 119 a. Bythis step, in the memory cell region MA, a source region MS comprised ofthe n⁻ type semiconductor region 119 a and the n⁺ type semiconductorregion 119 b is formed. In the peripheral circuit region PA, asource/drain region SD comprised of the n⁻ type semiconductor region 119a and the n⁺ type semiconductor region 119 b is formed.

Next, as shown in FIGS. 40 and 41, a metal silicide film SIL is formedon the control gate electrode portion CG, the memory gate electrodeportion MG, the source region MS, the drain region MD, and thesource/drain region SD by a salicide technology.

First, the silicon oxide film 112 is removed by wet etching or the like.This results in exposure of the control gate electrode portion CG, thememory gate electrode portion MG, the source region MS, the drain regionMD, and the source/drain region SD. Then, a metal film (not illustrated)is formed on the semiconductor substrate 100, followed by thermaltreatment of the semiconductor substrate 100 to cause a reaction betweenthe metal film and each of the control gate electrode portion CG, thememory gate electrode portion MG, the source region MS, the drain regionMD, and the source/drain region SD. As a result, a metal silicide filmSIL is formed on each of the control gate electrode portion CG, thememory gate electrode portion MG, the source region MS, the drain regionMD, and the source/drain region SD. The above-mentioned metal film ismade of, for example, nickel or nickel-platinum (Pt) alloy and can beformed using sputtering or the like. Then, an unreacted portion of themetal film is removed. The metal silicide film SIL thus formedcontributes to reduction in diffusion resistance or contact resistance.

Next, as shown in FIGS. 42 to 47, the polysilicon film 116 in theperipheral circuit region PA is substituted with a metal film 123 or thelike to form a gate electrode portion GE of the peripheral transistor.

First, as shown in FIGS. 42 and 43, a silicon oxide film 121 isdeposited as an interlayer insulating film over the control gateelectrode portion CG, the memory gate electrode portion MG, thepolysilicon film 116 by CVD or the like. Next, an upper portion of thissilicon oxide film 121 is removed until the surface of the siliconnitride film 117 is exposed. For example, an upper portion of thesilicon oxide film 121 is polished using, for example, CMP or the likeuntil exposure of the surface of the silicon nitride film 117. Aftercompletion of this step, the control gate electrode portion CG and thememory gate electrode portion MG have thereover the silicon oxide film121.

Next, the silicon nitride film 117 is removed using wet etching or thelike to expose the polysilicon film 116 in the peripheral circuit regionPA. Next, the polysilicon film 116 is removed by etching. By this step,a recess (trench, dent) TGE is provided in a gate electrode portionformation region of the peripheral transistor.

Next, as shown in FIGS. 44 and 45, a metal electrode film 122 and ametal film 123 are formed on the silicon oxide film 121 and also in therecess TGE. For example, a film of about 20 nm thick made of tantalumnitride/titanium/aluminum or the like is deposited as the metalelectrode film 122, followed by the formation of an aluminum film as themetal film 123. These films can be formed, for example, by sputtering.

Next, as shown in FIGS. 46 and 47, the metal electrode film 122 and themetal film 123 are removed until exposure of the surface of the siliconoxide film 121. For example, the metal electrode film 122 and the metalfilm 123 are polished using CMP or the like until exposure of thesurface of the silicon oxide film 121. By this step, the recess TGE isfilled with the metal film 123 via the metal electrode film 122. Thismeans that a gate electrode portion GE of the peripheral transistor isformed in the recess TGE. In other words, the polysilicon film 116 inthe peripheral circuit region PA is substituted by the stacked film ofthe metal electrode film 122 and the metal film 123.

As the metal electrode film 122, a metal material, for example, a metalfilm or a metal compound film (for example, a metal nitride film) havingconductivity can be used. This metal electrode film 122 configures ametal gate electrode. The metal electrode film 122 and the titaniumnitride film 115 (metal compound film or barrier film) lying therebelowcan also be regarded as the metal gate electrode. This titanium nitridefilm 115 (metal compound film or barrier film) functions as a barrierfilm for preventing diffusion of the metal material but it may beregarded as a part of the metal electrode film 122. The metal film 123on the metal electrode film 122 is formed for further reduction inresistance of the gate electrode portion GE.

In the present embodiment, an n channel type MISFET is described as anexample of the peripheral transistor, but a p channel type MISFET may beformed. The p channel type MISFET can be formed in a manner similar tothat of the n channel type MISFET except that the conductivity type isreversed. As a metal electrode film of the p channel type MISFET, a filmof about 20 nm thick made of tantalum nitride/titanium nitride/tantalumnitride can be used.

Next, as shown in FIGS. 48 and 49, a silicon oxide film 124 is depositedas an interlayer insulating film on the silicon oxide film 121 and onthe gate electrode portion GE by CVD or the like. Next, a plug (notillustrated) is formed in this silicon oxide film 124 and further, awiring 125 is formed on the silicon oxide film 124. The plug can beformed by filling, with a conductive film, a contact hole in theinterlayer insulating film. The wiring 125 can be formed, for example,by depositing a conductive film on the silicon oxide film 124 and thenpatterning it. Then, two or more wiring layers may be formed byrepeating the above-mentioned step of forming an interlayer insulatingfilm, a plug, and a wiring.

By the above-mentioned steps, the semiconductor device of the presentembodiment can be formed. Thus, by the above-mentioned steps, a memorycell (memory transistor, control transistor) formed in a memory cellregion MA and a peripheral transistor formed in a peripheral circuitregion PA and having a high-k insulating film and a metal electrode filmcan be formed efficiently on the same semiconductor substrate. In otherwords, both a memory cell (memory transistor, control transistor) and aperipheral transistor employing a high-k/metal configuration can beprovided on the same semiconductor substrate.

Second Embodiment

In the semiconductor device of First Embodiment, only the peripheraltransistor employs a high-k/metal configuration, but the controltransistor configuring the memory cell may employ this high-k/metalconfiguration.

The structure of a semiconductor device of the present embodiment willhereinafter be described referring to drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

(Description on the Structure of a Memory Cell)

FIG. 50 is a cross-sectional view showing the semiconductor device ofthe present embodiment. The semiconductor device of the presentembodiment has a configuration similar to that of First Embodiment(refer to FIG. 1 and the like) except that the control gate electrodeportion CG is comprised of a metal electrode film 122 and a metal film123 thereon. In the semiconductor device of the present embodiment,however, not a silicon oxide film 121 but a silicon oxide film 124 isarranged on the control gate electrode portion CG and the memory gateelectrode portion MG. In other words, the silicon oxide film 121 isarranged so as to fill between the control gate electrode portions CGand between the memory gate electrode portions MG and the silicon oxidefilm 121, the control gate electrode portion CG, and the memory gateelectrode portion MG have thereon the silicon oxide film 124. Thestructure will hereinafter be described more specifically.

As shown in FIG. 50, the memory cell is comprised of a controltransistor having a control gate electrode portion CG and a memorytransistor having a memory gate electrode portion MG.

More specifically, the memory cell has, similar to that of FirstEmbodiment, a control gate electrode portion CG provided over asemiconductor substrate 100 (p well PW) and a memory gate electrodeportion MG provided over the semiconductor substrate 100 (p well PW) andadjacent to the control gate electrode portion CG. For example, thememory gate electrode portion MG is made of a silicon film and thecontrol gate electrode portion CG is made of the metal electrode film122 and the metal film 123 thereon. The silicon film has thereover ametal silicide film SIL.

The memory cell further has an insulating film and a metal compound filmprovided between the control gate electrode portion CG and thesemiconductor substrate 100 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. The memory cell has, as the insulating film,a silicon oxide film 113 and a high-k insulating film (high dielectricconstant film) 114 and, as the metal compound film, a titanium nitridefilm 115 provided between the high-k insulating film 114 and the controlgate electrode portion CG.

The high-k insulating film (high dielectric constant film) 114 liesbetween the control gate electrode portion CG and the semiconductorsubstrate 100 (p well PW) and between the control gate electrode portionCG and the memory gate electrode portion MG.

The titanium nitride film 115 (metal compound film) lies between thecontrol gate electrode portion CG and the semiconductor substrate 100 (pwell PW) and between the control gate electrode portion CG and thememory gate electrode portion MG.

The memory cell further has an insulating film ONO (106, 107, 108)provided between the memory gate electrode portion MG and thesemiconductor substrate 100 (p well PW). The insulating film ONO iscomprised of, for example, a silicon oxide film 106, a silicon nitridefilm 107 thereon, and a silicon oxynitride film 108 thereon. The siliconnitride film 107 will serve as a charge accumulation portion.

The insulating film ONO (106, 107, 108) lie between the memory gateelectrode portion MG and the semiconductor substrate 100 (p well PW) andbetween the control gate electrode portion CG and the memory gateelectrode portion MG.

This means that the control gate electrode portion CG and the memorygate electrode portion MG have therebetween the insulating film ONO(106, 107, 108), the high-k insulating film (high dielectric constantfilm) 114, and the metal compound film (titanium nitride film 115) whichare provided successively from the side of the memory gate electrodeportion MG.

The memory cell further has a source region MS and a drain region MDformed in the p well PW of the semiconductor substrate 100. The memorygate electrode portion MG and the control gate electrode portion CGhave, on the sidewall portion of the synthesis pattern thereof, asidewall film (sidewall insulating film, sidewall spacer) SW made of aninsulating film.

Similar to First Embodiment, the source region MS is comprised of an n⁺type semiconductor region 119 b and an n⁻ type semiconductor region 119a and the drain region MD is comprised of an n⁺ type semiconductorregion 111 b and an n⁻ type semiconductor region 111 a. The memory gateelectrode portion MG, the source region MS (n⁺ type semiconductor region119 b), the drain region MD (n⁺ type semiconductor region 111 b) havethereover a metal silicide film SIL.

The memory cell has thereon a silicon oxide film 121 as an interlayerinsulating film and this silicon oxide film 121 has thereon a siliconoxide film 124 as an interlayer insulating film. The silicon oxide film124 has thereon a wiring 125 and the like.

The configuration of the peripheral transistor is similar to that ofFirst Embodiment so that a description on it is omitted. The operationexample of the memory cell is also similar to that of First Embodimentso that a description on it is omitted.

Thus, according to the present embodiment, since the control gateelectrode portion CG and the memory gate electrode portion MG havetherebetween the high-k insulating film (high dielectric constant film)114, the electric field intensity at the end portion (corner portion) ofthe memory gate electrode portion MG on the side of the control gateelectrode portion CG is relaxed upon erasing as in First Embodiment.This results in reduction in uneven distribution of charges in thecharge accumulation portion (silicon nitride film 107) and improvementin erase accuracy. In particular, erase accuracy can be improved evenwhen the erase operation is performed using the above-mentioned FNtunneling system.

In addition, the control transistor also employs the high-k/metalconfiguration, which is useful for reducing the resistance of thecontrol gate electrode portion and the power consumption of the controltransistor. As a result, the resulting control transistor can haveimproved characteristics.

In the present embodiment, an n-MOS type memory cell has been describedspecifically, but a p-MOS type memory cell having the configuration ofthe present embodiment can produce an advantage similar to that of then-MOS type memory cell. In addition, an n-MOS type transistor is used asthe peripheral transistor, but a p-MOS type transistor may be used asthe peripheral transistor. Both an n-MOS type transistor and a p-MOStype transistor may be formed in the peripheral circuit region PA.

Also to the semiconductor device of the present embodiment, theconfiguration of the memory array shown in FIGS. 4 and 5 or the circuitblock example shown in FIG. 6, each described in First Embodiment, canbe applied.

[Description on Manufacturing Method]

A method of manufacturing the semiconductor device of the presentembodiment will next be described while referring to FIGS. 51 to 57.FIGS. 51 to 57 are cross-sectional views showing manufacturing steps ofthe semiconductor device of the present embodiment.

A step of forming a memory cell in the memory cell region MA and aperipheral transistor in the peripheral circuit region PA willhereinafter be described.

Steps until the step of forming the silicon nitride film 117 are similarto those of First Embodiment (FIGS. 16 to 37). Described specifically,as in First Embodiment, an element isolation region (103) is formed inthe main surface of a semiconductor substrate 100 and a p well PW isformed in the semiconductor substrate 100. Next, as in First Embodiment,an insulating film ONO (106, 107, 108) and a memory gate electrodeportion MG (polysilicon film 109) in sidewall shape are formed. Next,after formation of a drain region MD and a sidewall film SW, a siliconoxide film 112 is formed between the polysilicon films 109. Next, asilicon oxide film 113, a high-k insulating film 114, and a titaniumnitride film 115 are formed on the semiconductor substrate 100, followedby the formation of a polysilicon film 116. Next, an upper portion ofthe polysilicon film 116 is removed. In such a manner, in the regionMMA, a memory gate electrode portion MG is formed via the insulatingfilm ONO (106, 107, 108), while in the region CCA, a polysilicon film116 is formed via the silicon oxide film 113, the high-k insulating film114, and the titanium nitride film 115. In the peripheral circuit regionPA, the polysilicon film 116 is formed via the silicon oxide film 113,the high-k insulating film 114, and the titanium nitride film 115.

Then, as shown in FIG. 51, a silicon nitride film 117 is deposited onthe polysilicon films 116 and 109 and the silicon oxide film 112 by CVDor the like.

Next, as shown in FIG. 52, by photolithography and dry etching, thesilicon nitride film 117 is left in the control gate electrode portionformation region and the region MMA in the memory cell region MA, whilethe silicon nitride film 117 is left in the gate electrode portionformation region in the peripheral circuit region PA. Then, with theresulting silicon nitride film 117 as a mask, the polysilicon film 116and the like are etched. The remaining polysilicon film 116 is apolysilicon film for substitution of a control gate electrode portion orfor substitution of a gate electrode portion.

Next, with the silicon nitride film 117 and the like as a mask, an ntype impurity such as arsenic (As) or phosphorus (P) is implanted intothe exposed portion of the semiconductor substrate 100 (p well PW) toform an n⁻ type semiconductor region 119 a. At this time, the n⁻ typesemiconductor region 119 a is formed in self alignment with the sidewallof the polysilicon film 116. Next, as in First Embodiment, a sidewallfilm (sidewall insulating film) SW is formed on the sidewall portion ofthe polysilicon film 116 and with the polysilicon film 116, the sidewallfilm SW, and the like as a mask, an n type impurity such as arsenic (As)or phosphorus (P) is implanted into the semiconductor substrate 100 (pwell PW) to form an n⁺ type semiconductor region 119 b in self alignmentwith the sidewall film SW. This n⁺ type semiconductor region 119 b hasan impurity concentration and a junction depth greater than those of then⁻ type semiconductor region 119 a. By this step, in the memory cellregion MA, a source region MS comprised of the n⁻ type semiconductorregion 119 a and the n⁺ type semiconductor region 119 b is formed. Inthe peripheral circuit region PA, a source/drain region SD comprised ofthe n⁻ type semiconductor region 119 a and the n⁺ type semiconductorregion 119 b is formed.

Next, as shown in FIG. 53, the silicon nitride film 117 on the memorygate electrode portion MG is removed and as in First Embodiment, a metalsilicide film SIL is formed (FIG. 54). First, the silicon nitride film117 is removed by wet etching or the like. As a result, the memory gateelectrode portion MG, the source region MS, the drain region MD, and thesource/drain region SD are exposed. Next, a metal film (not illustrated)is formed on the semiconductor substrate 100. The resultingsemiconductor substrate 100 is heat treated to cause a reaction betweenthe metal film and each of the memory gate electrode portion MG, thesource region MS, the drain region MD, and the source/drain region SD,resulting in formation of a metal silicide film SIL over each of thememory gate electrode portion MG, the source region MS, the drain regionMD, and the source/drain region SD.

Next, as shown in FIG. 55, a silicon oxide film 121 is deposited as aninterlayer insulating film over the memory gate electrode portion MG,the source region MS, the drain region MD, the source/drain region SD,and the polysilicon film 116 by CVD or the like. Next, an upper portionof the silicon oxide film 121 is removed until the surface of thesilicon nitride film 117 is exposed. For example, the upper portion ofthe silicon oxide film 121 is polished using CMP or the like until thesurface of the silicon nitride film 117 is exposed. Then, the siliconnitride film 117 is removed by wet etching or the like to expose thepolysilicon film 116 in the memory cell region MA and the peripheralcircuit region PA. Next, the polysilicon film 116 is removed by etching.By this step, a recess (trench, dent) TCG is provided in the controlgate electrode portion formation region and a recess TGE is provided inthe gate electrode portion formation region of the peripheraltransistor.

Next, as shown in FIG. 56, a metal electrode film 122 and a metal film123 are formed on the silicon oxide film 121 and also in the recessesTOG and TGE. For example, a film of about 20 nm thick made of tantalumnitride/titanium/aluminum or the like is deposited, followed by theformation of an aluminum film. These films can be formed, for example,by sputtering.

Next, as shown in FIG. 57, the metal electrode film 122 and the metalfilm 123 are removed until exposure of the surface of the silicon oxidefilm 121. For example, the metal electrode film 122 and the metal film123 are polished using CMP or the like until exposure of the surface ofthe silicon nitride film 117. By this step, the recesses TCG and TGE arefilled with the metal film 123 via the metal electrode film 122. Thismeans that a control gate electrode portion CG is formed in the recessTCG and a gate electrode portion GE of the peripheral transistor isformed in the recess TGE. In other words, the polysilicon film 116 inthe memory cell region MA is substituted by a stacked film of the metalelectrode film 122 and the metal film 123 and the polysilicon film 116in the peripheral circuit region PA is substituted by a stacked film ofthe metal electrode film 122 and the metal film 123.

Next, a silicon oxide film 124 is deposited as an interlayer insulatingfilm on the silicon oxide film 121, the gate electrode portion GE, andthe like by CVD or the like. Next, a plug (not illustrated) is formed inthis silicon oxide film 124 and further, a wiring 125 is formed on thesilicon oxide film 124 (refer to FIG. 50). The plug can be formed byfilling, with a conductive film, a contact hole in the interlayerinsulating film. The wiring 125 can be formed, for example, bydepositing a conductive film on the silicon oxide film 124 and thenpatterning it. Then, two or more wiring layers may be formed byperforming the step of forming the interlayer insulating film, plug, andwiring in repetition.

By the above-mentioned steps, the semiconductor device of the presentembodiment can be formed. Thus, by the above-mentioned steps, a memorycell formed in a memory cell region MA and having a control transistorhaving a high-k insulating film and a metal electrode film and aperipheral transistor formed in a peripheral circuit region PA andhaving a high-k insulating film and a metal electrode film can be formedefficiently on the same semiconductor substrate. In other words, both amemory cell employing a high-k/metal configuration and a peripheraltransistor employing a high-k/metal configuration can be provided on thesame semiconductor substrate.

Third Embodiment

In the semiconductor device of First Embodiment, only the peripheraltransistor uses a metal electrode film, but the memory transistor andthe control transistor configuring the memory cell may use the metalelectrode film.

The structure of a semiconductor device of the present embodiment willhereinafter be described referring to drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

(Description on Structure of Memory Cell)

FIG. 58 is a cross-sectional view showing the semiconductor device ofthe present embodiment. It has a configuration similar to that of FirstEmbodiment (refer to FIG. 1 and the like) except that each of the memorygate electrode portion MG and the control gate electrode portion CG iscomprised of a metal electrode film 122 and a metal film 123 thereon. Inthe semiconductor device of the present embodiment, however, the controlgate electrode portion CG and the memory gate electrode portion MG eachhave not thereon the silicon oxide film 121 but a silicon oxide film124. This means that the silicon oxide film 121 is arranged so as tofill between the control gate electrode portions CG and between thememory gate electrode portions MG. The silicon oxide film 121, thecontrol gate electrode portion CG, and the memory gate electrode portionMG have thereon the silicon oxide film 124. The structure of the presentembodiment will hereinafter be described in detail.

As shown in FIG. 58, the memory cell is comprised of a controltransistor having a control gate electrode portion CG and a memorytransistor having a memory gate electrode portion MG.

More specifically, the memory cell has, similar to that of FirstEmbodiment, a control gate electrode portion CG provided over asemiconductor substrate 100 (p well PW) and a memory gate electrodeportion MG provided over the semiconductor substrate 100 (p well PW) andadjacent to the control gate electrode portion CG. For example, thememory gate electrode portion MG and the control gate electrode portionCG are each made of a metal electrode film 122 and a metal film 123thereon.

The memory cell further has an insulating film and a metal compound filmprovided between the control gate electrode portion CG and thesemiconductor substrate 100 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. The memory cell has, as the insulating film,a silicon oxide film 113 and a high-k insulating film (high dielectricconstant film) 114 and, as the metal compound film, a titanium nitridefilm 115 provided between the high-k insulating film 114 and the controlgate electrode portion CG.

The high-k insulating film (high dielectric constant film) 114 liesbetween the control gate electrode portion CG and the semiconductorsubstrate 100 (p well PW) and between the control gate electrode portionCG and the memory gate electrode portion MG.

The titanium nitride film 115 (metal compound film) lies between thecontrol gate electrode portion CG and the semiconductor substrate 100 (pwell PW) and between the control gate electrode portion CG and thememory gate electrode portion MG.

The memory cell further has an insulating film ONO (106, 107, 108)provided between the memory gate electrode portion MG and thesemiconductor substrate 100 (p well PW). The insulating film ONO iscomprised of, for example, a silicon oxide film 106, a silicon nitridefilm 107 thereon, and a silicon oxynitride film 108 thereon. The siliconnitride film 107 will serve as a charge accumulation portion.

The insulating film ONO (106, 107, 108) lies between the memory gateelectrode portion MG and the semiconductor substrate 100(p well PW) andbetween the control gate electrode portion CG and the memory gateelectrode portion MG.

This means that the control gate electrode portion CG and the memorygate electrode portion MG have therebetween the insulating film ONO(106, 107, 108), the high-k insulating film (high dielectric constantfilm) 114, and the metal compound film (titanium nitride film 115)provided successively from the side of the memory gate electrode portionMG.

The memory cell further has a source region MS and a drain region MD inthe p well PW of the semiconductor substrate 100. The memory gateelectrode portion MG and the control gate electrode portion CG have, onthe sidewall portion of the synthesis pattern thereof, a sidewall film(sidewall insulating film, sidewall spacer) SW made of an insulatingfilm.

As in First Embodiment, the source region MS is comprised of the n⁺ typesemiconductor region 119 b and the n⁻ type semiconductor region 119 aand the drain region MD is comprised of the n⁺ type semiconductor region111 b and the n⁻ type semiconductor region 111 a. The source region MS(n type semiconductor region 119 b) and the drain region MD (n⁺ typesemiconductor region 111 b) have thereover a metal silicide film SIL.

The memory cell region MA has, as an interlayer insulating film, asilicon oxide film 121 and this silicon oxide film 121 has thereon asilicon oxide film 124 as an interlayer insulating film. This siliconoxide film 124 has thereon a wiring 125 and the like.

The configuration of the peripheral transistor is similar to that ofFirst Embodiment so that a description on it is omitted. An operationexample of the memory cell is also similar to that of First Embodimentso that a description on it is omitted.

In the present embodiment, since the control gate electrode portion CGand the memory gate electrode portion MG have therebetween the high-kinsulating film (high dielectric constant film) 114, an electric fieldintensity at the end portion (corner portion) of the memory gateelectrode portion MG on the side of the control gate electrode portionCG is relaxed upon erasing as in First Embodiment. This makes itpossible to reduce the uneven distribution of charges in the chargeaccumulation portion (silicon nitride film 107) and thereby improve theerase accuracy. In particular, erase accuracy can be improved even whenthe erase operation is performed using the above-mentioned FN tunnelingsystem.

In addition, using a metal electrode film also for the controltransistor and the memory transistor is effective for reducing theresistance of the control gate electrode portion and the memory gateelectrode portion and reducing the power consumption of thesetransistors. As a result, these transistors can have improvedcharacteristics.

In the present embodiment, an n-MOS type memory cell has been describedspecifically, but a p-MOS type memory cell having the configuration ofthe present embodiment can produce an advantage similar to that of then-MOS type memory cell. In addition, an n-MOS type transistor is shownas an example of a peripheral transistor, but a p-MOS type transistormay be used as the peripheral transistor. Both an n-MOS type transistorand a p-MOS type transistor may be formed in the peripheral circuitregion PA.

Also to the semiconductor device of the present embodiment, theconfiguration of the memory array shown in FIGS. 4 and 5 or the circuitblock example shown in FIG. 6, each described in First Embodiment, canbe applied.

[Description on Manufacturing Method]

A method of manufacturing the semiconductor device of the presentembodiment will next be described while referring to FIGS. 59 to 64.FIGS. 59 to 64 are cross-sectional views showing manufacturing steps ofthe semiconductor device of the present embodiment.

A step of forming a memory cell in the memory cell region MA and aperipheral transistor in the peripheral circuit region PA willhereinafter be described.

Steps until the step of forming a silicon nitride film 117 are similarto those of First Embodiment (FIGS. 16 to 37). Described specifically,as in First Embodiment, an element isolation region (103) is formed inthe main surface of a semiconductor substrate 100 and a p well PW isformed in the semiconductor substrate 100. Next, as in First Embodiment,an insulating film ONO (106, 107, 108) and polysilicon film 109 insidewall shape are formed. This polysilicon film 109 is a polysiliconfilm for substitution of a memory gate electrode portion. Next, afterformation of a drain region MD and a sidewall film SW, a silicon oxidefilm 112 is formed between the polysilicon films 109. Next, a siliconoxide film 113, a high-k insulating film 114, and a titanium nitridefilm 115 are formed on the semiconductor substrate 100, followed by theformation of a polysilicon film 116 thereon. Next, an upper portion ofthe polysilicon film 116 is removed. In such a manner, in the regionMMA, the polysilicon film 109 is formed via the insulating film ONO(106, 107, 108), while in the region CCA, the polysilicon film 116 isformed via the silicon oxide film 113, the high-k insulating film 114,and the titanium nitride film 115. In the peripheral circuit region PA,the polysilicon film 116 is formed via the silicon oxide film 113, thehigh-k insulating film 114, and the titanium nitride film 115. Thispolysilicon film 109 is a polysilicon film for substitution of a memorygate electrode portion. The polysilicon film 116 is a polysilicon filmfor substitution of a control gate electrode portion or substitution ofa gate electrode portion.

Then, as shown in FIG. 59, a silicon nitride film 117 is deposited onthe polysilicon films 116 and 109 and the silicon oxide film 112 by CVDor the like. Next, in the memory cell region MA, the silicon nitridefilm 117 is left in the control gate electrode portion formation regionand the region MMA by photolithography and etching. In the peripheralcircuit region PA, the silicon nitride film 117 is left in the gateelectrode portion formation region.

Next, with the silicon nitride film 117 and the like as a mask, an n⁻type semiconductor region 119 a is formed by the implantation of an ntype impurity such as arsenic (As) or phosphorus (P) into the exposedportion of the semiconductor substrate 100 (p well PW). At this time,the n⁻ type semiconductor region 119 a is formed in self alignment withthe sidewall of the polysilicon film 116. Next, as in First Embodiment,a sidewall film (sidewall insulating film) SW is formed on the sidewallportion of the polysilicon film 116 and with the polysilicon film 116,the sidewall film SW, and the like as a mask, an n type impurity such asarsenic (As) or phosphorus (P) is implanted into the semiconductorsubstrate 100 (p well PW). As a result, an n⁺ type semiconductor region119 b is formed in self alignment with the sidewall film SW. This n⁺type semiconductor region 119 b has an impurity concentration and ajunction depth greater than those of the n⁻ type semiconductor region119 a. By this step, in the memory cell region MA, a source region MScomprised of the n⁻ type semiconductor region 119 a and the n⁺ typesemiconductor region 119 b is formed. In the peripheral circuit regionPA, a source/drain region SD comprised of the n⁻ type semiconductorregion 119 a and the n⁺ type semiconductor region 119 b is formed.

Next, as shown in FIG. 60, the silicon oxide film 112 and the siliconnitride film 117 on the drain region MD (n⁺ type semiconductor region111 b) are removed and as in First Embodiment, a metal silicide film SILis formed (FIG. 61). For example, first, the silicon oxide film 112 andthe silicon nitride film 117 on the drain region D (n⁺ typesemiconductor region 111 b) are removed by wet etching or the like. As aresult, the source region MS, the drain region MD, and the source/drainregion SD are exposed. Next, a metal film (not illustrated) is formed onthe semiconductor substrate 100. The resulting semiconductor substrate100 is heat treated to cause a reaction between the metal film and eachof the source region MS, the drain region MD, and the source/drainregion SD, resulting in formation of a metal silicide film SIL over eachof the source region MS, the drain region MD, and the source/drainregion SD.

Next, as shown in FIG. 62, a silicon oxide film 121 is deposited as aninterlayer insulating film on the silicon nitride film 117 and the metalsilicide film SIL by CVD or the like. Next, an upper portion of thesilicon oxide film 121 is removed until the surface of the siliconnitride film 117 is exposed. For example, the upper portion of thesilicon oxide film 121 is polished using, for example, CMP until thesurface of the silicon nitride film 117 is exposed. Then, the siliconnitride film 117 is removed by wet etching or the like to expose thepolysilicon films 116 and 109 in the memory cell region MA and theperipheral circuit region PA. Next, the polysilicon films 116 and 109are removed by etching. By this step, as shown in FIG. 63, a recess(trench, dent) TMG is provided in a memory gate electrode portionformation region, a recess (trench, dent) TMG is provided in a controlgate electrode portion formation region, and a recess TGE is provided inthe gate electrode portion formation region of the peripheraltransistor.

Next, as shown in FIG. 64, a metal electrode film 122 and a metal film123 are formed on the silicon oxide film 121 and also in the recessesTMS, TCG and TGE. For example, a film of about 20 nm thick made oftantalum nitride/titanium/aluminum or the like is deposited, followed bythe formation of an aluminum film. These films can be formed, forexample, by sputtering.

Next, the metal electrode film 122 and the metal film 123 are removeduntil exposure of the surface of the silicon oxide film 121. Forexample, the metal electrode film 122 and the metal film 123 arepolished using CMP or the like until exposure of the surface of thesilicon oxide film 121. By this step, the recesses TMG, TCG and TGE arefilled with the metal film 123 via the metal electrode film 122. Thismeans that a memory gate electrode portion MG is formed in the recessTMG, a control gate electrode portion CG is formed in the recess TCG,and a gate electrode portion GE of the peripheral transistor is formedin the recess TGE. In other words, the polysilicon films 116 and 109 inthe memory cell region MA are substituted by a stacked film of the metalelectrode film 122 and the metal film 123, while the polysilicon film116 in the peripheral circuit region PA is substituted by a stacked filmof the metal electrode film 122 and the metal film 123.

Then, a silicon oxide film 124 is deposited as an interlayer insulatingfilm on the silicon oxide film 121, the gate electrode portion GE, andthe like by CVD or the like. Next, a plug (not illustrated) is formed inthis silicon oxide film 124 and further, a wiring 125 is formed on thesilicon oxide film 124 (refer to FIG. 58). The plug can be formed byfilling, with a conductive film, a contact hole in the interlayerinsulating film. The wiring 125 can be formed, for example, bydepositing a conductive film on the silicon oxide film 124 and thenpatterning it. Then, two or more wiring layers may be formed byperforming the above-mentioned step of forming the interlayer insulatingfilm, plug, and wiring in repetition.

By the above-mentioned steps, the semiconductor device of the presentembodiment can be formed. Thus, by the above-mentioned steps, a memorycell (memory transistor, control transistor) formed in a memory cellregion MA and having a high-k insulating film and a metal film and aperipheral transistor formed in a peripheral circuit region PA andhaving a high-k insulating film and a metal film can be formedefficiently on the same semiconductor substrate. In other words, both amemory cell (memory transistor, control transistor) employing ahigh-k/metal configuration and a peripheral transistor employing ahigh-k/metal configuration can be provided on the same semiconductorsubstrate.

Fourth Embodiment

In the present embodiment, both an n-MOS type transistor and a p-MOStype transistor are formed in the peripheral circuit region PA. A gateelectrode portion of the n-MOS type transistor in the peripheral circuitregion PA and the control gate electrode portion CG are made of the samematerial, while a gate electrode portion of the p-MOS type transistor inthe peripheral circuit region PA and the memory gate electrode portionMG are made of the same material.

The structure of the semiconductor device of the present embodiment willnext be described referring to drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

FIG. 65 is a cross-sectional view showing the semiconductor device ofthe present embodiment. The peripheral circuit region PA has, in aregion NTA thereof, an n-MOS type transistor and, in a region PTA, ap-MOS type transistor. The gate electrode portion GE of the n-MOS typetransistor and the control gate electrode portion CG are each made of ametal electrode film 122A and a metal film 123A thereon, while the gateelectrode portion GE of the p-MOS type transistor and the memory gateelectrode portion MG are each made of a metal electrode film 122B and ametal film 123B thereon. The other configuration is similar to that ofFirst Embodiment (refer to FIG. 1 and the like). The structure willhereinafter be described specifically.

As shown in FIG. 65, the memory cell is comprised of a controltransistor having the control gate electrode portion CG and a memorytransistor having the memory gate electrode portion MG.

Described specifically, the memory cell has, similar to that of FirstEmbodiment, a control gate electrode portion CG provided over asemiconductor substrate 100 (p well PW) and a memory gate electrodeportion MG provided over the semiconductor substrate 100 (p well PW) andadjacent to the control gate electrode portion CG. For example, thecontrol gate electrode portion CG is comprised of a metal electrode film122A and a metal film 123A thereon and the memory gate electrode MG iscomprised of a metal electrode film 122B and a metal film 123B thereon.

The metal electrode film 122A is made of, for example, tantalumnitride/titanium/aluminum. The metal electrode film 122B is made of, forexample, a tantalum nitride/titanium nitride/tantalum nitride. The metalfilm 123A and the metal film 123B are each made of an aluminum film butthey may be made of films different from each other.

The memory cell further has an insulating film and a metal compound filmprovided between the control gate electrode portion CG and thesemiconductor substrate 100 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. The memory cell has a silicon oxide film 113and a high-k insulating film (high dielectric constant film) 114 as theinsulating film. Further, the high-k insulating film 114 and the controlgate electrode portion CG have therebetween a titanium nitride film 115as the metal compound film.

The high-k insulating film (high dielectric constant film) 114 liesbetween the control gate electrode portion CG and the semiconductorsubstrate 100 (p well PW) and between the control gate electrode portionCG and the memory gate electrode portion MG.

The titanium nitride film 115 (metal compound film) lies between thecontrol gate electrode portion CG and the semiconductor substrate 100 (pwell PW) and between the control gate electrode portion CG and thememory gate electrode portion MG.

The memory cell further has an insulating film ONO (106, 107, 108)provided between the memory gate electrode portion MG and thesemiconductor substrate 100 (p well PW). The insulating film ONO iscomprised of, for example, a silicon oxide film 106, a silicon nitridefilm 107 thereon, and a silicon oxynitride film 108 thereon. The siliconnitride film 107 will serve as a charge accumulation portion.

The insulating film ONO (106, 107, 108) lies between the memory gateelectrode portion MG and the semiconductor substrate 100 (p well PW) andbetween the control gate electrode portion CG and the memory gateelectrode portion MG.

This means that the control gate electrode portion CG and the memorygate electrode portion MG have therebetween the insulating film ONO(106, 107, 108), the high-k insulating film (high dielectric constantfilm) 114 and the metal compound film (titanium nitride film 115) whichare provided successively from the side of the memory gate electrodeportion MG.

The memory cell further has a source region MS and a drain region MDformed in the p well PW of the semiconductor substrate 100. The memorygate electrode portion MG and the control gate electrode portion CGhave, on the sidewall portion of the synthesis pattern thereof, asidewall film (sidewall insulating film, sidewall spacer) SW made of aninsulating film.

The source region MS is, similar to that of First embodiment, comprisedof an n⁺ type semiconductor region 119 b and an n⁻ type semiconductorregion 119 a. The drain region MD is comprised of an n⁺ typesemiconductor region 111 b and an n⁻ type semiconductor region 111 a.The source region MS (n⁺ type semiconductor region 119 b) and the drainregion MD (n⁺ type semiconductor region 111 b) have thereover a metalsilicide film SIL.

The memory cell region MA has a silicon oxide film 121 as an interlayerinsulating film and this silicon oxide film 121 has thereon a siliconoxide film 124 as an interlayer insulating film. This silicon oxide film124 has thereon a wiring 125 and the like.

The peripheral circuit region PA has therein both an n-MOS typetransistor and a p-MOS type transistor. The n-MOS type transistor is ina region NTA, while the p-MOS type transistor is in a region PTA.

The n-MOS type transistor has a gate electrode portion GE arranged overthe semiconductor substrate 100 (p well PW) and a source/drain region SDsource provided in the p well PW on both sides of the gate electrodeportion GE. The gate electrode portion GE is comprised of a metalelectrode film 122A and a metal film 123A thereon. The peripheraltransistor has an insulating film and a metal compound film arrangedbetween the gate electrode portion GE and the semiconductor substrate100 (p well PW). The insulating film has a high dielectric constant filmhaving a dielectric constant higher than that of a silicon nitride film.The peripheral transistor has, as the insulating film, a silicon oxidefilm 113 and a high-k insulating film (high dielectric constant film)114 and, as the metal compound film, a titanium nitride film 115provided between the high-k insulating film 114 and the gate electrodeportion GE.

The gate electrode portion GE has, on the sidewall portion thereof, asidewall film SW made of an insulating film. The source/drain region SDis comprised of an n⁺ type semiconductor region 119 b and an n⁻ typesemiconductor region 119 a. The n⁻ type semiconductor region 119 a isformed in self alignment with the sidewall of the gate electrode portionGE. The n⁺ type semiconductor region 119 b is formed in self alignmentwith the side surface of the sidewall film SW and has a junction depthand an impurity concentration greater than those of the n⁻ typesemiconductor region 119 a. This source/drain region SD (n⁺ typesemiconductor region 119 b) has thereon a metal silicide film SIL.

The p-MOS type transistor has a gate electrode portion GE arranged overthe semiconductor substrate 100 (p well PW) and a source/drain region SDprovided in an n well NW on both sides of the gate electrode portion GE.The gate electrode portion GE is comprised of a metal electrode film122B and a metal film 123B thereon. The peripheral transistor has aninsulating film and a metal compound film arranged between the gateelectrode portion GE and the semiconductor substrate 100 (p well PW).The insulating film has a high dielectric film having a dielectricconstant higher than that of a silicon nitride film. The peripheraltransistor has, as the insulating film, a silicon oxide film 113 and ahigh-k insulating film (high dielectric constant film) 114 and, as themetal compound film, a titanium nitride film 115 provided between thehigh-k insulating film 114 and the gate electrode portion GE.

The gate electrode portion GE has, on the sidewall portion thereof, asidewall film SW made of an insulating film. The source/drain region SDis comprised of a p⁺ type semiconductor region 119 d and a p⁻ typesemiconductor region 119 c. The p⁻ type semiconductor region 119 c isformed in self alignment with the sidewall of the gate electrode portionGE. The p⁺ type semiconductor region 119 d is formed in self alignmentwith the side surface of the sidewall film SW and has a junction depthand an impurity concentration greater than those of the p⁻ typesemiconductor region 119 c. This source/drain region SD (p⁺ typesemiconductor region 119 d) has thereover a metal silicide film SIL.

The peripheral circuit region PA has therein a silicon oxide film 121 asan interlayer insulating film and this silicon oxide film 121 hasthereon a silicon oxide film 124 as an interlayer insulating film.

According to the present embodiment, since the control gate electrodeportion CG and the memory gate electrode portion MG have therebetweenthe high-k insulating film (high dielectric constant film) 114, anelectric field intensity at the end portion (corner portion) of thememory gate electrode portion MG on the side of the control gateelectrode portion CG is relaxed upon erasing, as in First Embodiment.This results in reduction in uneven distribution of charges in thecharge accumulation portion (silicon nitride film 107) and improvementin erase accuracy. In particular, erase accuracy can be improved evenwhen the erase operation is performed using the above-mentioned FNtunneling system.

In addition, since the control transistor and the memory transistor eachuses a metal electrode film, these transistors can have improvedcharacteristics due to reduction in the resistance of the control gateelectrode portion and the memory gate electrode portion and reduction inpower consumption of these transistors.

Further, since a film configuring the control gate electrode portion andthe memory gate electrode portion can be selected individually from ametal electrode film and a metal film, the threshold voltage of each ofthe transistors can be adjusted easily. For example, this makes itpossible to decrease the impurity concentration (channel implantation)below the gate electrode portion and thereby suppress variation in thethreshold voltage of each of the transistors.

Also to the semiconductor device of the present embodiment, theconfiguration of the memory array shown in FIGS. 4 and 5 or the circuitblock example shown in FIG. 6, each described in First Embodiment, canbe applied.

[Description on Manufacturing Method]

Next, a method of manufacturing the semiconductor device of the presentembodiment will be described. A step of forming a memory cell in thememory cell region MA and a peripheral transistor in the peripheralcircuit region PA will be described.

Steps until the step of forming a silicon oxide film 121 (refer to FIG.62) are similar to those of Third Embodiment so that a description onthem will be omitted.

Of the silicon nitride film 117 shown in FIG. 62, the silicon nitridefilm 117 in the region CCA and the region NTA are removed usingphotolithography and etching. The polysilicon film 116 in the region CCAand the region NTA is thereby exposed. Next, the polysilicon film 116 isremoved by etching. As a result, a recess (trench, dent) is provided inthe control gate electrode portion formation region and a recess isprovided in the gate electrode portion formation region in the regionNTA.

Next, the recess is filled with a metal film 123A via a metal electrodefilm 122A as in Third Embodiment. For example, after formation of a filmof about 20 nm thick made of, for example, a tantalumnitride/titanium/aluminum and an aluminum film on the semiconductorsubstrate, an upper portion of each of these films is polished using CMPor the like.

The polysilicon film 116 is then removed from the region MMA and theregion PTA by etching. As a result, a recess (trench, dent) is providedin the memory gate electrode portion formation region and a recess isprovided in the gate electrode portion formation region in the regionPTA.

As in Third Embodiment, the recess is then filled with a metal film 123Bvia a metal electrode film 122B. The metal electrode film 122B is madeof a material different from that of the metal electrode film 122A. Forexample, after formation of a film of about 20 nm thick made of, forexample, a tantalum nitride/titanium nitride/tantalum nitride and analuminum film on the semiconductor substrate, an upper portion of eachof these films is polished using CMP or the like.

Next, a silicon oxide film 124 is deposited as an interlayer insulatingfilm on the silicon oxide film 121, the gate electrode portion GE, andthe like by CVD or the like. Next, a plug (not illustrated) is formed inthis silicon oxide film 124 and further, a wiring 125 is formed in thesilicon oxide film 124 (refer to FIG. 65).

By the above-mentioned steps, the semiconductor device of the presentembodiment can be formed. Thus, by the above-mentioned steps, a memorycell (memory cell transistor, control transistor) formed in a memorycell region MA and having a high-k insulating film and a metal film anda peripheral transistor formed in a peripheral circuit region PA andhaving a high-k insulating film and a metal film can be formedefficiently on the same semiconductor substrate. In particular, memorycells having respectively different metal films and peripheraltransistors (n-MOS type transistor and p-MOS type transistor) havingrespectively different metal films can be formed efficiently on the samesemiconductor substrate.

Fifth Embodiment

In the semiconductor device of First Embodiment, the memory gateelectrode portion MG is formed in sidewall shape. The control gateelectrode portion CG may also be formed in sidewall shape.

The structure of a semiconductor device of the present embodiment willnext be described referring to drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

(Description on Structure of Memory Cell)

FIG. 66 is a cross-sectional view showing the semiconductor device ofthe present embodiment. As shown in FIG. 66, the memory cell iscomprised of a control transistor having a control gate electrodeportion CG and a memory transistor having a memory gate electrodeportion MG.

More specifically, the memory cell has a control gate electrode portionCG arranged over a semiconductor substrate 500 (p well PW) and a memorygate electrode portion MG arranged over the semiconductor substrate 500(P well PW) and adjacent to the control gate electrode portion CG. Forexample, the memory gate electrode portion MG is made of a silicon film,while the control gate electrode portion CG is made of a metal electrodefilm 516 and a metal film 517 thereon.

The memory cell further has an insulating film and a metal compound filmarranged between the control gate electrode portion CG and thesemiconductor substrate 500 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. As shown in FIG. 66, the memory cell has, asthe insulating film, a silicon oxide film 510 and a high-k insulatingfilm (high dielectric constant film) 511 and, as the metal compoundfilm, a titanium nitride film 512 provided the high-k insulating film511 and the control gate electrode portion CG.

The high-k insulating film (high dielectric constant film) 511 liesbetween the control gate electrode portion CG and the semiconductorsubstrate 500 (p well PW) and between the control gate electrode portionCG and the memory gate electrode portion MG.

The titanium nitride film 512 (metal compound film) lies between thecontrol gate electrode portion CG and the semiconductor substrate 500 (pwell PW) and between the control gate electrode portion CG and thememory gate electrode portion MG.

The memory cell further has an insulating film ONO (504, 505, 506)provided between the memory gate electrode portion MG and thesemiconductor substrate 500 (p well PW). The insulating film ONO is, forexample, comprised of a silicon oxide film 504, a silicon nitride film505 thereon, and a silicon oxynitride film 506 thereon. The siliconnitride film 505 will serves as a charge accumulation portion.

The insulating film ONO (504, 505, 506) lies between the memory gateelectrode portion MG and the semiconductor substrate 500 (p well PW).The memory gate electrode portion MG has thereon a silicon oxide film508. A stacked film of the insulating film ONO (504, 505, 506), thememory gate electrode portion MG, and the silicon oxide film 508 has, onthe sidewall thereof, a silicon oxide film 509 in sidewall shape.

This means that the control gate electrode portion CG and the memorygate electrode portion MG have therebetween the silicon oxide film 509,the high-k insulating film (high dielectric constant film) 511, and themetal compound film (titanium nitride film 512) which are providedsuccessively from the side of the memory gate electrode portion MG.

The memory cell further has a source region MS and a drain region MDformed in the p well PW of the semiconductor substrate 500.

The source region MS is comprised of an n⁺ type semiconductor region 514formed in self alignment with the side surface of the control gateelectrode portion CG and the drain region MD is comprised of an n⁺ typesemiconductor region 514 formed from below the side surface of thememory gate electrode portion MG.

The memory cell region MA has a silicon oxide film 515 as an interlayerinsulating film and this silicon oxide film 515 has thereon a siliconoxide film 518 as an interlayer insulating film. This silicon oxide film518 has thereon a wiring 520 and the like.

(Description on Structure of Peripheral Transistor)

As shown in FIG. 66, the peripheral transistor has a gate electrodeportion GE arranged over the semiconductor substrate 500 (p well PW) anda source/drain region SD provided in the p well PW on both sides of thegate electrode portion GE. The gate electrode portion GE is comprised ofa metal electrode film 516 and a metal film 517 thereon. The peripheraltransistor further has an insulating film and a metal compound filmarranged between the gate electrode portion GE and the semiconductorsubstrate 500 (p well PW). The insulating film has a high dielectricconstant film having a dielectric constant higher than that of a siliconnitride film. As shown in FIG. 66, the peripheral transistor has, as theinsulating film, a silicon oxide film 510 and a high-k insulating film(high dielectric constant film) 511 and, as the metal compound film, atitanium nitride film 512 between the high-k insulating film 511 and thegate electrode portion GE.

The source/drain region SD is comprised of an n⁺ type semiconductorregion 514. The n⁻ type semiconductor region 514 is formed in selfalignment with the sidewall of the gate electrode portion GE.

The peripheral circuit region PA has therein a silicon oxide film 515 asan interlayer insulating film and this silicon oxide film 515 hasthereon a silicon oxide film 518 as an interlayer insulating film.

Thus, in the present embodiment, the control gate electrode portion CGand the memory gate electrode portion MG have therebetween the high-kinsulating film (high dielectric constant film) 511 so that an electricfield intensity at an end portion (corner portion) of the memory gateelectrode portion MG on the side of the control gate electrode portionCG is relaxed upon erasing. This results in reduction in unevendistribution of charges in the charge accumulation portion (siliconnitride film 505) and improvement in erase accuracy.

In particular, when erase is performed through the FN tunneling system,compared with the BTBT system, the electric field at the end portion(corner portion) of the memory gate electrode portion MG on the side ofthe control gate electrode portion CG becomes greater, leading toconcentrated injection of many holes into this end portion. Thisfacilitates variation in the distribution of charges (holes, electrons)in the charge accumulation portion (silicon nitride film 505), which maydeteriorate the erase accuracy.

In the present embodiment, on the other hand, the control gate electrodeportion CG and the memory gate electrode portion MG have therebetweenthe high-k insulating film (high dielectric constant film) 511 so thatan electric field intensity at the end portion (corner portion) of thememory gate electrode portion MG on the side of the control gateelectrode portion is relaxed upon erasing. This results in improvementin erase accuracy.

Further, in the present embodiment, the control gate electrode portionCG and the memory gate electrode portion MG have therebetween thesilicon oxide film 509, the high-k insulating film (high dielectricconstant film) 511, and the metal compound film (titanium nitride film512) which are arranged successively from the side of the memory gateelectrode portion MG so that an electric field intensity at the endportion (corner portion) of the memory gate electrode portion MG on theside of the control gate electrode portion CG is relaxed upon erasing.This results in improvement in erase accuracy.

In the present embodiment, an n-MOS type memory cell has been describedin detail, but a p-MOS type memory cell having the configuration of thepresent embodiment produces an advantage similar to that of the n-MOStype memory cell. Also as an example of the peripheral transistor, ann-MOS type transistor is shown, but a p-MOS type transistor may be usedas the peripheral transistor or both an n-MOS type transistor and ap-MOS type transistor may be formed in the peripheral circuit region PA.

Also to the semiconductor device of the present embodiment, theconfiguration of the memory array shown in FIGS. 4 and 5 or the circuitblock example shown in FIG. 6, each described in First Embodiment, canbe applied.

[Description on Manufacturing Method]

Next, a method of manufacturing the semiconductor device of the presentembodiment will be described referring to FIGS. 67 to 78. FIGS. 67 to 78are cross-sectional views showing the manufacturing steps of thesemiconductor device of the present embodiment.

A step of forming a memory cell in the memory cell region MA and aperipheral transistor in the peripheral circuit region PA willhereinafter be described referring to these drawings.

First, an element isolation region is formed in the main surface of asemiconductor substrate 500. This element isolation region is formed, asin First Embodiment, by forming a silicon oxide film 501 and a siliconnitride film 502, each shown in FIG. 67, on the semiconductor substrate500, forming an element isolation trench (not illustrated), and fillingthe trench with a silicon oxide film.

Next, as shown in FIG. 68, a p well PW is formed in the semiconductorsubstrate 500. This p well PW is formed, as in First Embodiment, by theion implantation of a p type impurity (for example, boron (B)) via thesilicon oxide film 501.

Next, as shown in FIG. 69, an insulating film ONO (504, 505, 506) isformed on the semiconductor substrate 500 (p well PW), followed byformation of a polysilicon film 507 and a silicon oxide film 508thereon.

First, a silicon oxide film 504 is formed on the semiconductor substrate500. This silicon oxide film 504 is formed, for example, by thermaloxidation so as to have a thickness of about 4 nm. The silicon oxidefilm 504 may be formed using CVD or the like. Then, a silicon nitridefilm 505 of about 6 nm thick is deposited on the silicon oxide film 504,for example, by CVD. This silicon nitride film 505 becomes a chargeaccumulation portion of the memory cell and becomes an intermediatelayer configuring the insulating film ONO. Next, a silicon oxynitridefilm 506 of about 8 nm thick is deposited on the silicon nitride film505 by CVD or the like. As a result, the insulating film ONO comprisedof the silicon oxide film 504, the silicon nitride film 505, and thesilicon oxynitride film 506 can be formed.

Next, a polysilicon film 507 of about 40 nm thick is formed on thesilicon oxynitride film 506 (insulating film ONO) by CVD or the like.This polysilicon film 507 will be a memory gate electrode portion MG.Next, a silicon oxide film 508 of about 60 nm thick is formed on thepolysilicon film 507 by CVD or the like.

Next, as shown in FIG. 70, the insulating film ONO, polysilicon film507, and silicon oxide film 508 are patterned to form a memory gateelectrode portion MG. For example, a photoresist film (not illustrated)is formed in the memory gate electrode portion formation region on thesilicon oxide film 508 by photolithography and with this photoresistfilm as a mask, the insulating film ONO, polysilicon film 507, andsilicon oxide film 508 are etched. As a result, a memory gate electrodeportion MG comprised of the polysilicon film 507 is formed on thesemiconductor substrate 500 (p well PW) via the ONO film. The siliconoxide film 508 has remained on the memory gate electrode portion MG.This remaining silicon oxide film 508 may be called “cap insulatingfilm”.

Next, a silicon oxide film 509 in sidewall shape is formed on thesidewall of the memory gate electrode portion MG. This means that thesilicon oxide film 509 is formed on the sidewall portion of the stackedfilm of the insulating film ONO, polysilicon film 507, and silicon oxidefilm 508.

For example, a silicon oxide film 509 is deposited on the semiconductorsubstrate 500 (p well PW) and also the stacked film by CVD or like.Next, the silicon oxide film 509 of a predetermined thickness from thesurface thereof is removed by anisotropic dry etching to form a siliconoxide film (sidewall film) 509 in sidewall shape on the sidewall portionof the stacked film. The silicon oxide film (sidewall film) 509 referredherein has a single layer structure but it may have a stacked filmstructure. For example, a sidewall film having a three-layer structuremay be formed by successively depositing a silicon oxide film, a siliconnitride film, and a silicon oxide film on the semiconductor substrate500 (p well PW) and then, dry etching them anisotropically. Thus, usinga sidewall film having a stacked film structure can improve thebreakdown voltage between the memory gate electrode portion MG and thecontrol gate electrode portion CG further.

Next, as shown in FIG. 71, a high-k insulating film 511, a titaniumnitride film 512, and a polysilicon film 513 are formed on the siliconoxide film (sidewall film) 509 and the stacked film as well as on thesemiconductor substrate 500 (p well PW).

First, a silicon oxide film 510 is formed on the semiconductor substrate500. The silicon oxide film 510 is formed, for example, by thermaloxidation so as to have a thickness of about 1 nm. Then, a high-kinsulating film 511 is formed on the silicon oxide film (sidewall film)509 and the stacked film as well as on the silicon oxide film 510. Asthe high-k insulating film 511, for example, an Hf oxide film can beused. For example, an Hf oxide film of about 5 nm thick is depositedusing CVD or the like. Then, a titanium nitride film 512 of about 10 nmthick is deposited on the high-k insulating film 511 by CVD or the like.

Next, a polysilicon film 513 of about 40 nm thick is deposited on thetitanium nitride film 512 by CVD or the like. This polysilicon film 513will be a polysilicon film for substitution of a control gate electrodeportion. The control gate length (gate length of the control gateelectrode portion CG) is therefore determined according to thedeposition thickness of this polysilicon film 513.

Next, as shown in FIG. 72, the upper surface of the polysilicon film 513in the peripheral circuit region PA is covered with a mask (notillustrated) and the polysilicon film 513 in the memory cell region MAis etched back. By this etch back step, the polysilicon film 513 of apredetermined thickness from the surface thereof is removed byanisotropic dry etching. By this step, the polysilicon film 513 can beleft in sidewall shape (sidewall film shape) on both sides of the memorygate electrode portion MG (on both sides of the stacked film of theinsulating film ONO, polysilicon film 507, and silicon oxide film 508)via the silicon oxide film (sidewall film) 509, high-k insulating film511, and titanium nitride film 512. At this time, respective portions ofthe titanium nitride film 512, the high-k insulating film 511, and thesilicon oxide film 510 other than those arranged along the sidewallportion and below the polysilicon film 513 in sidewall shape areremoved. The polysilicon film 513 in sidewall shape located on the sideof the region CCA is a polysilicon film for substitution of a controlgate electrode portion. Next, the mask (not illustrated) is removed.

Next, as shown in FIG. 73, the polysilicon film 513 in the peripheralcircuit region PA is formed into that for the substitution of a gateelectrode portion while removing the polysilicon film 513 in sidewallshape located on the side of the region MMA. Next, a source region MSand a drain region MD of a memory cell and a source/drain region SD ofthe peripheral transistor are formed.

First, a photoresist film (not illustrated) is formed on the polysiliconfilm 513 in sidewall shape located in the region CCA and in the gateelectrode portion formation region of the peripheral transistor byphotolithography. With this photoresist film as a mask, the polysiliconfilm 513 located in the region MMA is etched. By this etching, thetitanium nitride film 512, the high-k insulating film 511, and thesilicon oxide film 510 below the polysilicon film 513 are removed. Thetitanium nitride film 512 and the high-k insulating film 511 arrangedalong the sidewall portion of the polysilicon film 513 remains along thesidewall portion of the memory gate electrode portion MG. The titaniumnitride film 512, the high-k insulating film 511, the silicon oxide film510, and the silicon oxide film 509 remaining along the sidewall portionof the memory gate electrode portion MG are called a sidewall residualfilm.

Next, an n type impurity such as arsenic (As) or phosphorus (P) isimplanted to form a source region MS and a drain region MD of the memorycell in the memory cell region MA and to form a source/drain region SDin the peripheral circuit region PA. More specifically, an n⁺ typesemiconductor region 514 is formed by the ion implantation of an n typeimpurity such as arsenic (As) or phosphorus (P) into an exposed portionof the semiconductor substrate 100 (p well PW) with the memory gateelectrode portion MG (including the sidewall residual film) and thepolysilicon film 513 as a mask. At this time, implantation conditions orthermal diffusion conditions of the n type impurity are adjusted so thatthe n type impurity diffuses, in the region MMA, from the lower portionof the sidewall residual film on the sidewall portion of the memory gateelectrode portion MG to the end portion of the memory gate electrodeportion MG. The n⁺ type semiconductor region 514 of the region MMA inthe memory cell region MA becomes a drain region MD of the memory celland the n⁺ type semiconductor region 514 of the region CCA in the memorycell region MA becomes a source region MS of the memory cell. The n⁺type semiconductor region 514 in the peripheral circuit region PAbecomes a source/drain region SD of the peripheral transistor. Since atthe memory gate electrode portion MG, the height is about 120 nm due tothe insulating film ONO, the polysilicon film 507, and the silicon oxidefilm 508, such a height can prevent, at the time of implantation of then type impurity, the impurity from penetrating and reaching the channelregion below the memory gate electrode portion MG.

After that, a metal silicide film (not illustrated) may be formed on thesource region MS and the drain region MD of the memory cell and thesource/drain region SD of the peripheral transistor by the salicidetechnology described in First Embodiment.

Next, as shown in FIGS. 74 to 78, the polysilicon film 513 issubstituted with a metal electrode film 516 or the like to form acontrol gate electrode portion CG of the memory cell and a gateelectrode portion GE of the peripheral transistor.

First, as shown in FIG. 74, a silicon oxide film 515 is deposited as aninterlayer insulating film on the polysilicon film 513 and the memorygate electrode portion MG by CVD or the like. Next, as shown in FIG. 75,an upper portion of this silicon oxide film 515 is polished using CMP orthe like until exposure of the surface of the polysilicon film 513 inthe memory cell region MA and the peripheral circuit region PA. Next, asshown in FIG. 76, the polysilicon film 513 is removed by etching. Bythis step, a recess (trench, dent) TCG is formed in the control gateelectrode portion formation region of the memory cell region MA and arecess (trench) TGE is formed in the gate electrode portion formationregion of the peripheral transistor in the peripheral circuit region PA.

Next, as shown in FIG. 77, a metal film 517 is formed, via a metalelectrode film 516, in the recesses TCG and TGE as well as on thesilicon oxide film 515. For example, after deposition of a film of about20 nm thick made of tantalum nitride/titanium/aluminum, an aluminum filmis formed. These films can be formed, for example, by sputtering.

Next, as shown in FIG. 78, the metal electrode film 516 and the metalfilm 517 are removed until the surface of the silicon oxide film 515 isexposed. For example, the metal electrode film 516 and the metal film517 are polished using CMP or the like until the surface of the siliconoxide film 515 is exposed. By this step, the recesses TCG and TGE arefilled with the metal film 517 via the metal electrode film 516. Thismeans that a control gate electrode portion CG of the memory cell isformed in the recess TCG and a gate electrode portion GE of theperipheral transistor is formed in the recess TGE. In other words, thepolysilicon film 513 in the memory cell region MA and the polysiliconfilm 513 in the peripheral circuit region PA are each substituted with astacked film of the metal electrode film 516 and the metal film 517.

Next, a silicon oxide film 518 is deposited as an interlayer insulatingfilm by CVD or the like on the silicon oxide film 515, the control gateelectrode portion CG, the gate electrode portion GE, and the like. Next,a plug is formed in the resulting silicon oxide films 515 and 518 andfurther, a wiring 520 is formed on the silicon oxide film 518 (refer toFIG. 66). The plug can be formed by embedding a conductive film in theinterlayer insulating film. The wiring 520 can be formed, for example,by depositing a conductive film on the silicon oxide film 518 and thenpatterning it. Two or more wiring layers may thereafter be formed byrepeating the step of forming an interlayer insulating film, a plug, anda wiring.

By the above-mentioned steps, the semiconductor device of the presentembodiment can be formed. Thus, by the above-mentioned steps, a memorycell formed in a memory cell region MA and having a high-k insulatingfilm and a metal film and a peripheral transistor formed in a peripheralcircuit region PA and having a high-k insulating film and a metal filmcan be formed efficiently on the same semiconductor substrate. In otherwords, both a memory cell employing a high-k/metal configuration for thecontrol transistor thereof and a peripheral transistor employing ahigh-k/metal configuration can be provided on the same semiconductorsubstrate.

According to the present embodiment, the polysilicon film 105 describedin First Embodiment, that is, a film configuring a sidewall upon formingthe memory gate electrode portion MG in sidewall shape becomesunnecessary. The step of forming or removing the polysilicon film 105therefore becomes unnecessary, making it possible to simplify themanufacturing steps of the semiconductor device.

Sixth Embodiment

In Fifth Embodiment, after formation of an element isolation region inthe main surface of a semiconductor substrate, an insulating film ONO isformed on the semiconductor substrate. Alternatively, an elementisolation region may be formed after formation of an insulating film ONOon a semiconductor substrate.

The structure of a semiconductor device of the present embodiment willhereinafter be described referring to drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

FIGS. 79 and 80 are cross-sectional views showing the semiconductordevice of the present embodiment. The drawing on the left (portion A-A)of FIG. 79 corresponds to the cross-section A-A of FIG. 4, the centraldrawing (portion B-B) of FIG. 79 corresponds to the B-B cross-section ofFIG. 4, and the drawing on the right of FIG. 79 corresponds to the C-Ccross-section.

As shown in FIG. 79, the memory cell is comprised of a controltransistor having a control gate electrode portion CG and a memorytransistor having a memory gate electrode portion MG. As shown in thedrawing on the left of FIG. 79, the memory cell of the presentembodiment has a configuration similar to that of Fifth Embodiment (FIG.66).

Described specifically, the memory cell has a control gate electrodeportion CG arranged over a semiconductor substrate 600 (p well PW) and amemory gate electrode portion MG arranged over the semiconductorsubstrate 600 (p well PW) and adjacent to the control gate electrodeportion CG. For example, the memory gate electrode portion MG is made ofsilicon films (604 and 607), while the control gate electrode portion CGis made of a metal electrode film 616 and a metal film 617 thereon.

The memory cell further has an insulating film and a metal compound filmarranged between the control gate electrode portion CG and thesemiconductor substrate 600 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. As shown in FIG. 79, the memory cell has, asthe insulating film, a silicon oxide film 610 and a high-k insulatingfilm (high dielectric constant film) 611. Further, the high-k insulatingfilm 611 and the control gate electrode portion CG have therebetween atitanium nitride film 612 as the metal compound film.

The high-k insulating film (high dielectric constant film) 611 lie'sbetween the control gate electrode portion CG and the semiconductorsubstrate 600 (p well PW) and between the control gate electrode portionCG and the memory gate electrode portion MG.

The titanium nitride film 612 (metal compound film) lies between thecontrol gate electrode portion CG and the semiconductor substrate 600 (pwell PW) and between the control gate electrode portion CG and thememory gate electrode portion MG.

The memory cell further has an insulating film ONO (601, 602, 603)arranged between the memory gate electrode portion MG and thesemiconductor substrate 600 (p well PW). The insulating film ONO iscomprised of, for example, a silicon oxide film 601, a silicon nitridefilm 602 thereon, and a silicon oxynitride film 603 thereon. The siliconnitride film 602 will serve as a charge accumulation portion.

The insulating film ONO (601, 602, 603) lies between the memory gateelectrode portion MG and the semiconductor substrate 600 (p well PW).This memory gate electrode portion MG has thereon a silicon oxide film608. A stacked film of the insulating film ONO (601, 602, 603), thememory gate electrode portion MG, and the silicon oxide film 608 has, onthe sidewall thereof, a silicon oxide film 609 in sidewall shape.

This means that the control gate electrode portion CG and the memorygate electrode portion MG have therebetween the silicon oxide film 609,the high-k insulating film. (high dielectric constant film) 611, and themetal compound film (titanium nitride film 612) which are providedsuccessively from the side of the memory gate electrode portion MG.

The memory cell further has a source region MS and a drain region MDformed in the p well PW of the semiconductor substrate 600.

The source region MS is comprised of an n⁺ type semiconductor region 614formed in self alignment with the side surface of the control gateelectrode portion CG and the drain region MD is comprised of an n⁺ typesemiconductor region 614 formed from below the side surface of thememory gate electrode portion MG.

The memory cell region MA has, as an interlayer insulating film, asilicon oxide film 615 and further, this silicon oxide film 615 hasthereon a silicon oxide film 618 as an interlayer insulating film. Thissilicon oxide film 618 has thereon a wiring 620 and the like.

In the present embodiment, however, as shown in the central drawing ofFIG. 79, an element isolation region 606 penetrates through theinsulating film ONO and reaches the middle of the semiconductorsubstrate.

In First Embodiment, as described referring to FIG. 4, the activeregions (hatched portion) are provided in a line shape extending indirection X and memory cell arrays are arranged. A plurality of memorycell arrays is arranged in direction Y (gate-width direction). In thecross-section B-B in the central drawing of FIG. 79, the active regions(exposed regions of the p well PW) and the element isolation regions 606are arranged alternately. In the present embodiment, the elementisolation regions 606 are formed so as to penetrate through theinsulating film ONO. The active regions in a line shape extending indirection X are coupled to each other via a coupling portion extendingin direction Y so that this coupling portion has thereon the insulatingfilm ONO.

The peripheral transistor shown in FIG. 80 has a configuration similarto that of Fifth Embodiment (FIG. 66) so that a description on it isomitted. The operation example of the memory cell is similar to that ofFirst Embodiment so that a description on it is omitted.

According to the present embodiment, similar to Fifth Embodiment, thecontrol gate electrode portion CG and the memory gate electrode portionMG have therebetween the high-k insulating film (high dielectricconstant film) 611 so that an electric field intensity at the endportion (corner portion) of the memory gate electrode portion MG on theside of the control gate electrode portion CG is relaxed upon erasing.This makes it possible to reduce uneven distribution of charges in thecharge accumulation portion (silicon nitride film 602) and therebyimprove the erase accuracy. In particular, erase accuracy can beimproved even when the erase operation is performed using theabove-mentioned FN tunneling system.

In addition, the control transistor also employs the high-k/metalconfiguration to reduce the resistance of the control gate electrodeportion CG and reduce the power consumption of the control transistor.As a result, the resulting control transistor can have improvedcharacteristics.

In the present embodiment, the element isolation region 606 penetratesthrough the insulating film ONO so that diffusion of charges via theinsulating film ONO on the element isolation region 606 can besuppressed. As a result, the memory cell can have improved operationcharacteristics.

In the present embodiment, an n-MOS type memory cell has been describedin detail, but a p-MOS type memory cell having the configuration of thepresent embodiment produces an advantage similar to that of the n-MOStype memory cell. Also as an example of the peripheral transistor, ann-MOS type transistor is shown, but a p-MOS type transistor may be usedas the peripheral transistor or both an n-MOS type transistor and ap-MOS type transistor may be formed in the peripheral circuit region PA.

[Description on Manufacturing Method]

Next, a manufacturing method of the semiconductor device of the presentembodiment will be described referring to FIGS. 81 to 98. FIGS. 81 to 98are cross-sectional views showing manufacturing steps of thesemiconductor device of the present embodiment.

Referring to the drawings, a step of forming a memory cell in the memorycell region MA and a peripheral transistor in the peripheral circuitregion PA will hereinafter be described.

First, as shown in FIGS. 81 and 82, after formation of a p well PW in asemiconductor substrate 600 and formation of an insulating film ONOcomprised of a silicon oxide film 601, a silicon nitride film 602, and asilicon oxynitride film 603 on the semiconductor substrate 600, anelement isolation region 606 is formed in the main surface of thesemiconductor substrate 600.

More specifically, the p well PW in the semiconductor substrate 600 canbe formed by the ion implantation of a p type impurity (for example,boron (B)) in the semiconductor substrate 600 in a manner similar tothat of First Embodiment.

Next, an insulating film ONO (601, 602, 603) is formed on thesemiconductor substrate 600 (p well PW), followed by the formation of apolysilicon film 604 and a silicon nitride film 605 thereon. First, asilicon oxide film 601 is formed on the semiconductor substrate 600.This silicon oxide film 601 is formed, for example, by thermal oxidationso as to have a thickness of about 4 nm. The silicon oxide film 601 maybe formed using CVD or the like. Then, a silicon nitride film 602 ofabout 6 nm thick is deposited on the silicon oxide film 601, forexample, by CVD. This silicon nitride film 602 becomes a chargeaccumulation portion of the memory cell and becomes an intermediatelayer configuring the insulating film ONO. Next, a silicon oxynitridefilm 603 of about 8 nm thick is deposited on the silicon nitride film602 by CVD or the like. As a result, the insulating film ONO comprisedof the silicon oxide film 601, the silicon nitride film 602, and thesilicon oxynitride film 603 can be formed.

Then, a polysilicon film 604 of about 20 nm thick is formed on thesilicon oxynitride film 603 (insulating film ONO) by CVD or the like.This polysilicon film 604 will be a portion of a memory gate electrodeportion MG. Then, a silicon nitride film 605 of about 50 nm thick isformed on the polysilicon film 604 by CVD or the like.

Next, an element isolation region 606 is formed. This element isolationregion 606 can be formed using STI described in First Embodiment.Described specifically, an element isolation trench of about 150 nm deeppenetrating through the silicon nitride film 605, the polysilicon film604, and the insulating film ONO and reaching the semiconductorsubstrate 600 (p well PW) is formed and the trench is filled with asilicon oxide film to form the element isolation region 606.

Next, as shown in FIGS. 83 and 84, after removal of the silicon nitridefilm 605, a polysilicon film 607 having a thickness equal to or greaterthan the removed silicon nitride film 605 is formed on the elementisolation region 606 and the polysilicon film 604. As a result, aplurality of polysilicon films 604 isolated by the element isolationregion 606 is coupled to each other by the polysilicon film 607. Thesetwo layers of the polysilicon films 604 and 607 will be a memory gateelectrode portion MG. Then, a silicon oxide film 608 is formed on thepolysilicon film 607 by CVD or the like.

Next, as shown in FIGS. 85 and 86, a photoresist film (not illustrated)is formed in the memory gate electrode portion formation region byphotolithography. With this photoresist film as a mask, the siliconoxide film 608, the polysilicon films 607 and 604, and the insulatingfilm ONO are dry etched. As a result, a memory gate electrode portion MG(polysilicon films 604 and 607) are formed on the semiconductorsubstrate 600 (p well PW) via the insulating film ONO. This memory gateelectrode portion MG has thereon the residual silicon oxide film 608.

Next, a silicon oxide film 609 in sidewall shape is formed on thesidewall of the memory gate electrode portion MG as in Fifth Embodiment.Next, a silicon oxide film 610 is formed on the semiconductor substrate600 and then, a high-k insulating film 611, a titanium nitride film 612,and a polysilicon film 613 are formed as in Fifth Embodiment on thesemiconductor substrate 600 (p well PW) including on the silicon oxidefilm (sidewall film) 609 and the silicon oxide film 608.

Next, as shown in FIGS. 87 and 88, the upper surface of the polysiliconfilm 613 in the peripheral circuit region PA is covered with a mask film(not illustrated) and the polysilicon film 613 in the memory cell regionMA is etched back. In this etch back step, as in Fifth Embodiment, thepolysilicon film 613 of a predetermined film thickness from the surfacethereof is removed by anisotropic dry etching. By this step, thepolysilicon film 613 can be left in sidewall shape (sidewall film shape)on both sides (both sides of the stacked film of the insulating filmONO, the polysilicon films 601 and 607, and the silicon oxide film 608)of the memory gate electrode portion MG via the silicon oxide film(sidewall film) 609, the high-k insulating film 611, and the titaniumnitride film 612. The polysilicon film 613 in sidewall shape located onthe side of the region CCA is a polysilicon film for substitution of acontrol gate electrode portion. Next, the above-mentioned mask (notillustrated) is removed.

Next, as shown in FIGS. 89 and 90, a polysilicon film 613 forsubstitution of a gate electrode portion is formed in the peripheralcircuit region PA while removing the polysilicon film 613 in sidewallshape located on the side of the region MMA. Next, a source region MSand a drain region MD of the memory cell and a source/drain region SD ofthe peripheral transistor are formed. These steps are similar to thoseof Fifth Embodiment.

After that, a metal silicide film (not illustrated) may be formed on thesource region MS and the drain region MD of the memory cell and thesource/drain region SD of the peripheral transistor by the salicidetechnology described in First Embodiment.

Next, as shown in FIGS. 91 to 98, the polysilicon film 613 issubstituted with a metal electrode film 616 and the like to form acontrol gate electrode portion CG of the memory cell and a gateelectrode portion GE of the peripheral transistor.

First, as shown in FIGS. 91 and 92, a silicon oxide film 615 is formedas an interlayer insulating film on the polysilicon film 613 and thesilicon oxide film 608 by CVD or the like. Next, as shown in FIGS. 93and 94, an upper portion of this silicon oxide film 615 is polishedusing CMP or the like until the surface of the polysilicon film 613 inthe memory cell region MA and the peripheral circuit region PA isexposed. Next, the polysilicon film 613 is removed by etching. By thisstep, as shown in FIGS. 95 and 96, a recess (trench, dent) TCG is formedin the control gate electrode portion formation region of the memorycell region MA and a recess (trench, dent) TGE is formed in the gateelectrode portion formation region of the peripheral transistor in theperipheral circuit region PA.

Next, as in Fifth Embodiment, a metal film 617 is formed, via the metalelectrode film 616, in the recess TCG and the recess TGE as well as onthe silicon oxide film 615. Next, as shown in FIGS. 97 and 98, the metalelectrode film 616 and the metal film 617 are removed by CMP or the likeuntil the surface of the silicon oxide film 615 is exposed. Thus, byfilling the recess TCG and the recess TGE with the metal film 617 viathe metal electrode film 616, the control gate electrode portion CG ofthe memory cell and the gate electrode portion GE of the peripheraltransistor are formed.

Next, as in Fifth Embodiment, a silicon oxide film 618 is deposited asan interlayer insulating film by CVD or the like on the silicon oxidefilm 615, the silicon oxide film 608, the control gate electrode portionCG, and the gate electrode portion GE. Next, a plug (not illustrated) isformed in the resulting silicon oxide film 618 and further, a wiring 620(refer to FIGS. 79 and 80) is formed on the silicon oxide film 618. Twoor more wiring layers may thereafter be formed by repeating the step offorming an interlayer insulating film, a plug, and a wiring.

By the above-mentioned steps, the semiconductor device of the presentembodiment can be formed. Thus, by the above-mentioned steps, a memorycell formed in a memory cell region MA and having a control transistorhaving a high-k insulating film and a metal electrode film and aperipheral transistor formed in a peripheral circuit region PA andhaving a high-k insulating film and a metal electrode film can be formedefficiently on the same semiconductor substrate. In other words, both amemory cell employing, for a control transistor thereof, a high-k/metalconfiguration and a peripheral transistor employing a high-k/metalconfiguration can be loaded on the same semiconductor substrate.

According to the present embodiment, the polysilicon film 105 describedin First Embodiment, that is, a film configuring a sidewall upon formingthe memory gate electrode portion MG in sidewall shape becomesunnecessary. The step of forming or removing the polysilicon film 105therefore becomes unnecessary, making it possible to simplify themanufacturing steps of the semiconductor device.

In addition, according to the present embodiment, by forming the elementisolation region after formation of the insulating film ONO on thesemiconductor substrate, the element isolation region 606 can be formedso that it penetrates through the insulating film ONO. This makes itpossible to suppress, as described above, diffusion of charges via theinsulating film ONO on the element isolation region 606 and therebyprovide a memory cell having improved operation characteristics.

Seventh Embodiment

In Fifth Embodiment, after formation of the polysilicon film 513 insidewall shape (sidewall film shape), via the silicon oxide film 509 andthe like, on both sides of the memory gate electrode portion MG, thepolysilicon film 513 located on the side of the region MMA is removed,but this polysilicon film may be left. The structure of a semiconductordevice of the present embodiment will hereinafter be described referringto drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

FIG. 99 is a cross-sectional view showing the semiconductor device ofthe present embodiment. As shown in FIG. 99, the memory cell of thepresent embodiment is comprised of a control transistor having a controlgate electrode portion CG and a memory transistor having a memory gateelectrode portion MG.

The present embodiment is similar to Fifth Embodiment (FIG. 66) exceptthat the region MMA has therein a dummy control gate electrode portionDCG.

Described specifically, the memory cell has a control gate electrodeportion CG arranged over a semiconductor substrate 700 (p well PW), amemory gate electrode portion MG arranged over the semiconductorsubstrate 700 (p well PW) and adjacent to the control gate electrodeportion CG, and a dummy control gate electrode portion DCG arranged overthe semiconductor substrate 700 (p well PW) and adjacent to the memorygate electrode portion MG. For example, the memory gate electrodeportion MG is made of a silicon film, while the control gate electrodeportion CG is made of a metal electrode film 716 and a metal film 717thereon. The dummy control gate electrode portion DCG is made of a metalelectrode film 716 and a metal film 717 thereon.

The memory cell further has an insulating film and a metal compound filmarranged between the control gate electrode portion CG and thesemiconductor substrate 700 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. As shown in FIG. 99, the memory cell has, asthe insulating film, a silicon oxide film 710 and a high-k insulatingfilm (high dielectric constant film) 711. Further, the high-k insulatingfilm 711 and the control gate electrode portion CG have therebetween atitanium nitride film 712 as the metal compound film.

The high-k insulating film (high dielectric constant film) 711 liesbetween the control gate electrode portion CG and the semiconductorsubstrate 700 (p well PW) and between the control gate electrode portionCG and the memory gate electrode portion MG.

The titanium nitride film 712 (metal compound film) lies between thecontrol gate electrode portion CG and the semiconductor substrate 700 (pwell PW) and between the control gate electrode portion CG and thememory gate electrode portion MG.

The memory cell further has an insulating film and a metal compound filmarranged between the dummy control gate electrode portion DCG and thesemiconductor substrate 700 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. As shown in FIG. 99, the memory cell has, asthe insulating film, a silicon oxide film 710 and a high-k insulatingfilm (high dielectric constant film) 711. Further, the high-k insulatingfilm 711 and the dummy control gate electrode portion DCG havetherebetween a titanium nitride film 712 as the metal compound film.

The high-k insulating film (high dielectric constant film) 711 liesbetween the dummy control gate electrode portion DCG and thesemiconductor substrate 700 (p well PW) and between the dummy controlgate electrode portion DCG and the memory gate electrode portion MG.

The titanium nitride film 712 (metal compound film) lies between thedummy control gate electrode portion DCG and the semiconductor substrate700 (p well PW) and between the dummy control gate electrode portion DCGand the memory gate electrode portion MG.

The memory cell further has an insulating film ONO (704, 705, 706)arranged between the memory gate electrode portion MG and thesemiconductor substrate 700 (p well PW). The insulating film ONO iscomprised of, for example, a silicon oxide film 704, a silicon nitridefilm 705 thereon, and a silicon oxynitride film 706 thereon. The siliconnitride film 705 will serve as a charge accumulation portion.

The insulating film ONO (704, 705, 706) lies between the memory gateelectrode portion MG and the semiconductor substrate 700 (p well 2W).This memory gate electrode portion MG has thereon a silicon oxide film708. A stacked film of the insulating film ONO (704, 705, 706), thememory gate electrode portion MG, and the silicon oxide film 708 has, onthe sidewall thereof, a silicon oxide film 709 in sidewall shape.

This means that the control gate electrode portion CG and the memorygate electrode portion MG have therebetween the silicon oxide film 709,the high-k insulating film (high dielectric constant film) 711, and themetal compound film (titanium nitride film 712) which are providedsuccessively from the side of the memory gate electrode portion MG.

The memory cell further has a source region MS and a drain region MDformed in the p well PW of the semiconductor substrate 700.

The source region MS is comprised of an n⁺ type semiconductor region 714formed in self alignment with the side surface of the control gateelectrode portion CG and the drain region MD is comprised of an n⁺ typesemiconductor region 714 formed from below the side surface of thememory gate electrode portion MG. This drain region MD has thereover thedummy control gate electrode portion DCG. This dummy control gateelectrode portion DCG however does not contribute to the operation ofthe memory cell. For example, upon operation of the memory cell, thedummy control gate electrode portion DCG is controlled so as not tocontribute to the operation of the memory cell by setting it at floatingor fixed potential (for example, ground potential of 0 V).

The memory cell region MA has, as an interlayer insulating film, asilicon oxide film 715 and this silicon oxide film 715 has thereon asilicon oxide film 718 as an interlayer insulating film. This siliconoxide film 718 has thereon a wiring 720 and the like.

The peripheral transistor of the present embodiment is similar to thatof Fifth Embodiment (FIG. 66) so that a description on it is omitted.The operation example of the memory cell is similar to that of FirstEmbodiment except for the control of the above-mentioned dummy controlgate electrode portion DCG so that a description on it is omitted.

According to the present embodiment, similar to Fifth Embodiment, thecontrol gate electrode portion CG and the memory gate electrode portionMG have therebetween the high-k insulating film (high dielectricconstant film) 711 so that an electric field intensity at the endportion (corner portion) of the memory gate electrode portion MG on theside of the control gate electrode portion CG is relaxed upon erasing.This makes it possible to reduce uneven distribution of charges in thecharge accumulation portion (silicon nitride film 705) and therebyimprove the erase accuracy. In particular, erase accuracy can beimproved even when the erase operation is performed using theabove-mentioned FN tunneling system.

In addition, the control transistor also employs the high-k/metalconfiguration to reduce the resistance of the control gate electrodeportion CG and reduce the power consumption of the control transistor.As a result, the resulting control transistor can have improvedcharacteristics.

In the present embodiment, an n-MOS type memory cell has been describedin detail, but a p-MOS type memory cell having the configuration of thepresent embodiment produces an advantage similar to that of the n-MOStype memory cell. Also as an example of the peripheral transistor, ann-MOS type transistor is shown, but a p-MOS type transistor may be usedas the peripheral transistor or both an n-MOS type transistor and ap-MOS type transistor may be formed in the peripheral circuit region PA.

Also to the semiconductor device of the present embodiment, theconfiguration of the memory array shown in FIGS. 4 and 5 or the circuitblock example shown in FIG. 6, each described in First Embodiment, canbe applied.

[Description on Manufacturing Method]

Next, a method of manufacturing the semiconductor device (FIG. 99) ofthe present embodiment will be described. In the present embodiment, asource region MS and a drain region MD of the memory cell and asource/drain region SD of the peripheral transistor are formed whileleaving the polysilicon film (513) in sidewall shape on both sides ofthe memory gate electrode portion MG as shown in FIG. 72 in Fifth.Embodiment. Next, as in Fifth Embodiment, the polysilicon film (513) issubstituted with a metal electrode film 716 and a metal film 717 thereonto form a control gate electrode portion CG and a dummy control gateelectrode portion DCG of the memory cell and a gate electrode portion GEof the peripheral transistor.

Thus, by the above-mentioned steps, a step of removing the polysiliconfilm (513) described in Fifth Embodiment becomes unnecessary. This cansimplify the manufacturing steps of the semiconductor device.

Eighth Embodiment

In the semiconductor device of Fifth Embodiment, only the peripheraltransistor uses a metal electrode film. It is also possible that thememory transistor and the control transistor configuring the memory celluse the metal electrode film.

The structure of the semiconductor device of the present embodiment willhereinafter be described referring to drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

FIG. 100 is a cross-sectional view showing the semiconductor device ofthe present embodiment. As shown in FIG. 100, the memory cell iscomprised of a control transistor having a control gate electrodeportion CG and a memory transistor having a memory gate electrodeportion MG.

The semiconductor device of the present embodiment is similar to that ofFifth Embodiment except for the configuration of the memory gateelectrode portion MG so that only the memory gate electrode portion MGwill be described and a description on the other configuration will beomitted.

As shown in FIG. 100, the memory gate electrode portion MG is, similarto the control gate electrode portion CG or a gate electrode portion GEof the peripheral transistor, comprised of a metal electrode film 817and a metal film 818 lying thereon.

Thus, the semiconductor device of the present embodiment has aconfiguration similar to that of Fifth Embodiment so that as in FifthEmbodiment, the semiconductor device can have improved erase accuracy.

In addition, in the semiconductor device of the present embodiment, thecontrol transistor and the memory transistor also use a metal electrodefilm. This makes it possible to reduce the resistance of the controlgate electrode portion and the memory gate electrode portion and reducethe power consumption of these transistors. As a result, the transistorsthus obtained can have improved characteristics.

[Description on Manufacturing Method]

Next, a method of manufacturing the semiconductor device of the presentembodiment will be described referring to FIGS. 101 to 104. FIGS. 101 to104 are cross-sectional views showing manufacturing steps of thesemiconductor device of the present embodiment.

A step of forming a memory cell in a memory cell region MA and aperipheral transistor in a peripheral circuit region will hereinafter bedescribed referring to drawings.

As in Fifth Embodiment, an element isolation region and a p well PW areformed in a semiconductor substrate 800.

Next, as shown in FIG. 101, an insulating film ONO (804, 805, 806) isformed on the semiconductor substrate 800 (p well PW). Then, a stopperfilm ES is formed on the insulating film ONO.

Described specifically, a silicon oxide film 804 is formed on thesemiconductor substrate 800. This silicon oxide film 804 is formed, forexample, by thermal oxidation so as to have a thickness of about 4 nm.The silicon oxide film 804 may be formed using CVD or the like. Next, asilicon nitride film 805 of about 6 nm thick is deposited on the siliconoxide film 804, for example, by CVD. This silicon nitride film 805 willserve as a charge accumulation portion of the memory cell and become anintermediate layer configuring the insulating film ONO. A siliconoxynitride film 806 of about 8 nm thick is then deposited on the siliconnitride film 805 by CVD. As a result, the insulating film ONO comprisedof the silicon oxide film 804, the silicon nitride film 805, and thesilicon oxynitride film 806 can be formed.

Next, a silicon nitride film of about 5 nm thick is deposited as astopper film ES by CVD or the like on the silicon oxynitride film 806(insulating film ONO).

Next, a polysilicon film 807 of about 80 nm thick is formed on thestopper film ES by CVD or the like. Then, a silicon oxide film 808 ofabout 20 nm thick is formed on the polysilicon film 807 by CVD or thelike.

Next, as shown in FIG. 102, as in Fifth Embodiment, the insulating filmONO, the stopper film ES, the polysilicon film 807, and the siliconoxide film 808 are patterned to form a polysilicon film 807 forsubstitution of a memory gate electrode portion. Next, a silicon oxidefilm 809 in sidewall shape is formed, as in Fifth Embodiment, on thesidewall of the polysilicon film 807 for substitution of a memory gateelectrode portion.

Next, as shown in FIG. 103, as in Fifth Embodiment, a recess (trench,dent) TCG is provided in a control gate electrode portion formationregion and a recess (trench, dent) TGE is provided in a gate electrodeportion formation region of the peripheral transistor. At this time, arecess (trench, dent) TMG is also provided in a memory gate electrodeportion formation region.

For example, as in Fifth Embodiment, after formation of a silicon oxidefilm 810, a high-k insulating film 811, a titanium nitride film 812, anda polysilicon film for substitution (not illustrated), these films areleft (not illustrated) in sidewall shape on both sides of thepolysilicon film 807 for substitution of a memory gate electrodeportion. From the polysilicon film for substitution in sidewall shape, aportion thereof located on the side of the region MMA is removed. Theremaining polysilicon film for substitution will be a polysilicon filmfor substitution of the control gate electrode portion or the gateelectrode portion. Then, a source region MS and a drain region MD of thememory cell and a source/drain region SD of the peripheral transistorare formed. Next, a silicon oxide film 816 is formed as an interlayerinsulating film and an upper portion of the silicon oxide film 816 ispolished using CMP or the like until exposure of the surface of thepolysilicon film for substitution. By this treatment, the silicon oxidefilm 808 is removed and the polysilicon film for substitution and thepolysilicon film 807 are exposed.

Next, the polysilicon film for substitution and the polysilicon film 807are removed by etching to form a recess (trench, dent) TMG in the memorygate electrode portion formation region, a recess (trench, dent) TCG inthe control gate electrode portion formation region and a recess(trench, dent) TGE in the gate electrode portion formation region of theperipheral transistor. Upon the above-mentioned etching, the stopperfilm (silicon nitride film) ES at the bottom of the recess (trench,dent) in the memory gate electrode portion formation region is removed(FIG. 103).

Next, as in Fifth Embodiment, the recesses TMG, TCG, and TGE are filledwith a metal film 818 via a metal film 817. First as shown in FIG. 104,a metal film 818 is formed in the recesses TMG, TCG, and TGE as well ason the silicon oxide film 816 via the metal electrode film 817. Then,the metal electrode film 817 and the metal film 818 are polished usingCMP or the like until exposure of the surface of the silicon oxide film816. As a result, a memory gate electrode portion MG of the memory cellis formed in the recess TMG; a control gate electrode portion CG of thememory cell is formed in the recess TCG; and a gate electrode portion GEof the peripheral transistor is formed in the recess TGE.

Next, a silicon oxide film 819 is formed as an interlayer insulatingfilm on the silicon oxide film 816 by CVD or the like. Then, a plug isformed in these silicon oxide films 816 and 819, followed by theformation of a wiring 821 on the silicon oxide film 819 (refer to FIG.100).

By the above-mentioned steps, the semiconductor device of the presentinvention can be formed. Thus, by these steps, a memory cell formed in amemory cell region MA and having a high-k insulating film and a metalelectrode film and a peripheral transistor formed in a peripheralcircuit region PA and having a high-k insulating film and a metalelectrode film can be formed efficiently on the same semiconductorsubstrate.

Ninth Embodiment

The structure of a semiconductor device of the present embodiment willhereinafter be described referring to drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

(Description on Structure of Memory Cell)

FIG. 105 is a cross-sectional view showing the semiconductor device ofthe present embodiment. As shown in FIG. 105, the memory cell iscomprised of a control transistor having a control gate electrodeportion CG and a memory transistor having a memory gate electrodeportion MG.

Described specifically, the memory cell has a control gate electrodeportion CG arranged over a semiconductor substrate 900 (p well PW) and amemory gate electrode portion MG arranged over the semiconductorsubstrate 900 (p well PW) and adjacent to the control gate electrodeportion CG. For example, the memory gate electrode portion MG is made ofa silicon film, while the control gate electrode portion CG is made of ametal electrode film 916 and a metal film 917 thereon. The memory cellfurther has an insulating film and a metal compound film providedbetween the control gate electrode portion CG and the semiconductorsubstrate 900 (p well PW). The insulating film has a high dielectricconstant film having a dielectric constant higher than that of a siliconnitride film. As shown in FIG. 105, the memory cell has, as theinsulating film, a silicon oxide film 904 and a high-k insulating film(high dielectric constant film) 905. Further, the high-k insulating film905 and the control gate electrode portion CG have therebetween atitanium nitride film 906 as the metal compound film.

The memory cell further has an insulating film ONO (909, 910, 911)arranged between the memory gate electrode portion MG and thesemiconductor substrate 900 (p well PW). The insulating film ONO iscomprised of, for example, a silicon oxide film 909, a silicon nitridefilm 910 thereon, and a silicon oxynitride film 911 thereon. The siliconnitride film 910 will serve as a charge accumulation portion.

The insulating film ONO (909, 910, 911) is arranged between the memorygate electrode portion MG and the semiconductor substrate 900 (p wellPW), between the control gate electrode portion CG and the memory gateelectrode portion MG, and between the memory gate electrode portion MGand the silicon oxide film 915. This means that the insulating film ONOis arranged so as to extend along the sidewall and bottom surface of arecess made of the sidewall of the control gate electrode portion CG,the semiconductor substrate 900 (p well PW), and the sidewall of thesilicon oxide film 915. In other words, the insulating film ONO (909,910, 911) extends between the memory gate electrode portion MG and thesemiconductor substrate 900 (p well PW), between the control gateelectrode portion CG and the memory gate electrode portion MG, and alongthe side surface of the memory gate electrode portion MG on the sideopposite to the control gate electrode portion CG. The recess has, onthe bottom surface thereof, a dent. This dent is provided so that itbecomes deeper from the outer periphery of the bottom surface of therecess to the center portion.

The memory cell further has a source region MS and a drain region MDformed in the p well PW of the semiconductor substrate 900.

The source region MS is comprised of an n⁺ type semiconductor region 914formed in self alignment with the side surface of the control gateelectrode portion CG and the drain region MD is comprised of an n⁻ typesemiconductor region 914 formed from below the insulating film ONOarranged along the side surface of the memory gate electrode portion MG.

The memory cell region MA has, as an interlayer insulating film, asilicon oxide film 915 and this silicon oxide film 915 has thereon asilicon oxide film 918 as an interlayer insulating film. This siliconoxide film 918 has thereon a wiring 920 and the like.

(Description on Structure of Peripheral Transistor)

As shown in FIG. 105, the peripheral transistor has a gate electrodeportion GE arranged over the semiconductor substrate 900 (p well PW) anda source/drain region SD provided in the p well PW on both sides of thegate electrode portion GE. The gate electrode portion GE is comprised ofa metal electrode film 916 and a metal film 917 thereon. The peripheraltransistor further has an insulating film and a metal compound filmarranged between the gate electrode portion GE and the semiconductorsubstrate 900 (p well PW). The insulating film has a high dielectricconstant film having a dielectric constant higher than that of a siliconnitride film. The peripheral transistor has, as the insulating film, asilicon oxide film 904 and a high-k insulating film (high dielectricconstant film) 905. The high-k insulating film 905 and the gateelectrode portion GE have therebetween a titanium nitride film 906 asthe metal compound film.

The source/drain region SD is comprised of an n⁺ type semiconductorregion 914. The n⁻ type semiconductor region 914 is formed in selfalignment with the sidewall of the gate electrode portion GE.

The peripheral circuit region PA has therein a silicon oxide film 915 asan interlayer insulating film and this silicon oxide film 915 hasthereon a silicon oxide film 918 as an interlayer insulating film.

Thus, in the present embodiment, the insulating film ONO is arranged onthe dent of the semiconductor substrate 900 so that electric fieldagainst the insulating film ONO upon erasing increases. Compared withusing the semiconductor substrate 900 which is flat without having arecess therein, the present embodiment can improve the erase speed.Thus, the memory cell can have improved operation characteristics.

In the present embodiment, an n-MOS type memory cell has been describedin detail, but a p-MOS type memory cell having the configuration of thepresent embodiment produces an advantage similar to that of the n-MOStype memory cell. Also as an example of the peripheral transistor, ann-MOS type transistor is shown, but a p-MOS type transistor may be usedas the peripheral transistor or both an n-MOS type transistor and ap-MOS type transistor may be formed in the peripheral circuit region PA.

The operation example of the memory cell is similar to that of FirstEmbodiment so that a description on it is omitted.

Also to the semiconductor device of the present embodiment, theconfiguration of the memory array shown in FIGS. 4 and 5 or the circuitblock example shown in FIG. 6, each described in First Embodiment, canbe applied.

[Description on Manufacturing Method]

Next, a method of manufacturing the semiconductor device of the presentembodiment will next be described referring to FIGS. 106 to 114. FIGS.106 to 114 are cross-sectional views showing the manufacturing steps ofthe semiconductor device of the present embodiment.

A step of forming a memory cell in a memory cell region MA and aperipheral transistor in a peripheral circuit region PA will hereinafterbe described referring to these drawings.

First, an element isolation region (not illustrated) is formed in themain surface of a semiconductor substrate 900. This element isolationregion is formed as in First Embodiment. Then, as shown in FIG. 106, a pwell PW is formed in the semiconductor substrate 900. This p well PW isformed, as in First Embodiment, by the ion implantation.

Next, a silicon oxide film 904 is formed on the semiconductor substrate(p well PW) 900 and a high-k insulating film 905 is then formed on thissilicon oxide film 904. Described specifically, a silicon oxide film 904of about 1 nm thick is formed on the semiconductor substrate 900 (p wellPW) by thermal oxidation. Then, a high-k insulating film 905 is formedon the silicon oxide film 904. As the high-k insulating film 905, forexample, an Hf oxide film can be used. For example, an Hf oxide film ofabout 5 nm thick is deposited using CVD or the like.

Then, a titanium nitride film 906 of about 10 nm thick is deposited onthe high-k insulating film 905 by CVD or the like.

A polysilicon film 907 of about 100 nm thick is then deposited on thetitanium nitride film 906 by CVD or the like. Next, a silicon oxide film908 of about 20 nm thick is formed on the polysilicon film 907 by CVD orthe like.

Next, as shown in FIG. 107, the silicon oxide film 908, the polysiliconfilm 907, the titanium nitride film 906, the high-k insulating film 905,and the silicon oxide film 904 in the memory gate electrode portionformation region are removed using photolithography and dry etching toform a recess (trench, dent) TMG. At this time, etching is performeduntil a dent is formed in the surface of the semiconductor substrate 900(p well PW). The dent thus provided becomes gradually deeper from theouter periphery of the bottom surface of the recess (trench, dent) TMGto the center portion.

Next, as shown in FIG. 108, an insulating film ONO (909, 910, 911) and apolysilicon film 912 are formed in the recess (trench, dent) TMG as wellas on the silicon oxide film 908. Described specifically, first asilicon oxide film of about 4 nm thick is deposited in the recess(trench, dent) TMG as well as on the silicon oxide film 908, forexample, by CVD. Then, a silicon nitride film 910 of about 6 nm thick isdeposited on the silicon oxide film 909, for example, by CVD. Thissilicon nitride film 910 will be a charge accumulation portion of thememory cell and becomes an intermediate layer configuring the insulatingfilm ONO. Next, a silicon oxynitride film 911 of about 8 nm thick isdeposited on the silicon nitride film 910 by CVD or the like.

Next, a polysilicon film 912 having a thickness enough to fill therecess (trench, dent) TMG therewith is deposited on the insulating filmONO (909, 910, 911) by CVD or the like.

Next, as shown in FIG. 109, a memory gate electrode portion MG isformed. For example, the surface of the polysilicon film 912 is etchedback. At this time, this etchback is performed until the thickness ofthe polysilicon film 912 in the recess (trench, dent) TMG becomes belowthe thickness of the polysilicon film 907. By this step, the polysiliconfilm 912 formed in the recess (trench, dent) TMG will be a memory gateelectrode portion MG.

Next, a silicon oxide film 913 is deposited on the insulating film ONO(909, 910, 911) and the polysilicon film 912 by CVD or the like. Then,an upper portion of the silicon oxide film 913 is removed until exposureof the surface of the polysilicon film 907 by CMP or the like.

Next, as shown in FIG. 110, a polysilicon film 907 for substitution of acontrol gate electrode portion and a polysilicon film 907 for thesubstitution of a gate electrode portion are formed. First, aphotoresist film (not illustrated) covering therewith the control gateelectrode portion formation region and the upper surface of the recessTMG and a photoresist film (not illustrated) covering therewith the gateelectrode portion formation region are formed using photolithography.Next, with these photoresist films as a mask, the polysilicon film 907,the titanium nitride film 906, the high-k insulating film 905, and thesilicon oxide film 904 are etched (FIG. 110). As a result, thepolysilicon film 907 is formed adjacent to the memory gate electrodeportion MG via the insulating film ONO. This polysilicon film 907 willbe a polysilicon film for substitution of a control gate electrodeportion. The polysilicon film 907 in the peripheral circuit region PAwill be a polysilicon film for substitution of a gate electrode portion.

Next, a source region MS and a drain region MD of the memory cell and asource/drain region SD of the peripheral transistor are formed.Described specifically, with the silicon oxide film 913 and thepolysilicon film 907 on the memory gate electrode portion MG as a mask,an n type impurity such as arsenic (As) or phosphorus (P) is implantedinto the exposed portion of the semiconductor substrate 900 (p well PW)to form an n⁺ type semiconductor region 914. The n⁺ type semiconductorregion 914 between the memory gate electrode portions MG will be a drainregion MD of the memory cell and the n⁺ type semiconductor region 914 onthe side of the polysilicon film 907 in the memory cell region MA willbe a source region MS of the memory cell. The n⁺ type semiconductorregion 914 in the peripheral circuit region PA will be a source/drainregion SD of the peripheral transistor. Upon this impurity implantation,since the height including that of the silicon oxide film 913 arrangedon the memory gate electrode portion MG is as high as about 120 nm, an ntype impurity can be prevented from penetrating and reaching the channelregion below the memory gate electrode portion MG upon implantation ofit.

The source region MS, the drain region MD, and the source/drain regionSD of the peripheral transistor may be formed so as to have an LDDstructure by forming a sidewall film on the sidewall of the polysiliconfilm 907 (refer to First Embodiment). A metal silicide film (notillustrated) may be formed on the source region MS and the drain regionMD of the memory cell and the source/drain region SD of the peripheraltransistor by the salicide technology described in First Embodiment.

Next, as shown in FIG. 111, a silicon oxide film 915 is formed as aninterlayer insulating film over the polysilicon film 907 and the memorygate electrode portion MG by CVD or the like. Next, as shown in FIG.112, an upper portion of this silicon oxide film 915 is polished usingCMP or the like until the surface of the polysilicon film 907 isexposed.

Next, as shown in FIG. 113, the polysilicon film 907 is removed byetching. By this step, a recess (trench, dent) TCG is provided in thecontrol gate electrode portion formation region and a recess TGE isprovided in the gate electrode portion formation region of theperipheral transistor.

Next, as shown in FIG. 114, a metal electrode film 916 and a metal film917 are formed in the recesses TCG and TGE as well as on the siliconoxide film 915. For example, after deposition of a film of about 20 nmthick made of tantalum nitride/titanium/aluminum, an aluminum film isformed. These films can be formed, for example, by sputtering. Then, themetal electrode film 916 and the metal film 917 are removed using CMP orthe like until exposure of the surface of the silicon oxide film 915.

By this step, the recesses TCG and TEG are filled with the metal film917 via the metal electrode film 916. In other words, a control gateelectrode portion CG is formed in the recess TCG and a gate electrodeportion GE of the peripheral transistor is formed in the recess TGE.

Then, a silicon oxide film 918 is deposited as an interlayer insulatingfilm on the silicon oxide film 915, the gate electrode portion GE, andthe like by CVD or the like. Then, a plug (not illustrate) is formed inthis silicon oxide film 918 and a wiring 920 is formed on the siliconoxide film 918 (refer to FIG. 105).

By the above-mentioned steps, the semiconductor device of the presentembodiment can be formed. Thus, by the above-mentioned steps, a memorycell formed in a memory cell region MA and having a high-k insulatingfilm and a metal electrode film and a peripheral transistor formed in aperipheral circuit region PA and having a control transistor having ahigh-k insulating film and a metal electrode film can be formedefficiently on the same semiconductor substrate. In other words, both amemory cell employing a high-k/metal configuration and a peripheraltransistor employing a high-k/metal configuration can be loaded on thesame semiconductor substrate.

In addition, by the above-mentioned steps, a semiconductor device havingimproved erase characteristics can be provided by forming a dent (TMG)in a semiconductor substrate and arranging an insulating film ONO on thedent.

Tenth Embodiment

In Ninth Embodiment, a stacked film of the metal electrode film 916 andthe metal film 917 thereon is formed only on one side of the memory gateelectrode portion MG, but the stacked film of the metal electrode film916 and the metal film 917 thereon may be formed on both sides of thememory gate electrode portion MG.

The structure of the semiconductor device of the present embodiment willhereinafter be described referring to some drawings.

FIG. 115 is a cross-sectional view showing the semiconductor device ofthe present embodiment. As shown in FIG. 115, a memory cell is comprisedof a control transistor having a control gate electrode portion CG and amemory transistor having a memory gate electrode portion MG.

In the present embodiment, the memory gate electrode portion MG has acontrol gate electrode portion arranged adjacent to one side of thememory gate electrode portion MG and a dummy control gate electrodeportion DCG arranged adjacent to the other side thereof.

The memory gate electrode portion MG is made of a silicon film, whilethe control gate electrode portion CG is made of a metal electrode film916 and a metal film 917 thereon. The dummy control gate electrodeportion DCG is comprised of a metal electrode film 916 and a metal film917 thereon.

The memory cell further has an insulating film and a metal compound filmbetween the control gate electrode portion CG and the semiconductorsubstrate 900 (p well PW). The insulating film has a high dielectricconstant film having a dielectric constant higher than that of a siliconnitride film. The memory cell has, as the insulating film, a siliconoxide film 904 and a high-k insulating film (high dielectric constantfilm) 905. The high-k insulating film 905 and the control gate electrodeportion CG have therebetween a titanium nitride film 906 as the metalcompound film.

The memory cell further has an insulating film and a metal compound filmbetween the dummy control gate electrode portion DCG and thesemiconductor substrate 900 (p well PW). The insulating film has a highdielectric constant film having a dielectric constant higher than thatof a silicon nitride film. The memory cell has, as the insulating film,a silicon oxide film 904 and a high-k insulating film (high dielectricconstant film) 905. The high-k insulating film 905 and the control gateelectrode portion CG have therebetween a titanium nitride film 906 asthe metal compound film.

The memory cell further has an insulating film ONO (909, 910, 911)arranged between the memory gate electrode portion MG and thesemiconductor substrate 900 (p well PW). The insulating film ONO iscomprised of, for example, a silicon oxide film 909, a silicon nitridefilm 910 lying thereon, and a silicon oxynitride film 911 lying thereon.The silicon nitride film 910 will be a charge accumulation portion.

The memory cell further has a source region MS and a drain region MDformed in the p well PW of the semiconductor substrate 700.

The source region MS is comprised of an n⁺ type semiconductor region 914formed in self alignment with the side surface of the control gateelectrode portion CG and the drain region MD is comprised of an n⁺ typesemiconductor region 914 formed from below the side surface of thememory gate electrode portion MG. The drain region MD has thereover thedummy control gate electrode portion DCG. This dummy control gateelectrode portion DCG does not contribute to the operation of the memorycell. For example, upon operation of the memory cell, the dummy controlgate electrode portion DCG is controlled so as not to contribute to theoperation of the memory cell by placing it under a floating state.

Such a manufacturing step of the semiconductor device is performed inthe following manner. For example, patterning is performed so as toleave the polysilicon film 907 on both sides of the memory gateelectrode portion MG in the step shown in FIG. 110 in Ninth Embodiment.A source region MS and a drain region MD of the memory cell and asource/drain region SD of the peripheral transistor are formed whileleaving the polysilicon film 907 on both sides of the memory gateelectrode portion MG. Then, as in Ninth Embodiment, the polysilicon film907 is substituted with the metal electrode film 916 and the metal film917.

Thus, by providing the control gate electrode portion CG on one side ofthe memory gate electrode portion MG and providing the dummy controlgate electrode portion DCG on the other side, variation in thresholdvoltage due to disturb stress can be suppressed. In other words, itleads to improvement in disturb resistance.

In the present embodiment, the memory gate electrode portion MG and thedrain region MD where hot carriers causing disturb are generated have,between them, the dummy control gate electrode portion DCG. Presence ofthis dummy control gate electrode portion DCG is presumed to suppressthe influence of the hot carriers.

Eleventh Embodiment

In First Embodiment, the peripheral transistor has employed ahigh-k/metal configuration. Alternatively, some of the peripheraltransistors may use a gate electrode portion GE made of, for example, asilicon film without using the high-k metal configuration.

The structure of a semiconductor device of the present embodiment willnext be described referring to some drawings.

[Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

FIG. 116 is a cross-sectional view showing the configuration of some ofthe peripheral transistors of the semiconductor device of the presentembodiment. The semiconductor device of the present embodiment issimilar to that of First Embodiment in the other configuration, that is,the configuration of the memory cell and the configuration of the otherperipheral transistors.

As shown in FIG. 116, some of the peripheral transistors of thesemiconductor device of the present embodiment have a gate electrodeportion GE arranged over a semiconductor substrate 1100 (p well PW) anda source/drain region SD provided in the p well PW on both sides of thegate electrode portion GE. The gate electrode portion GE is made of asilicon film. This silicon film has thereover a metal silicide film SIL.The peripheral transistor has an insulating film and a metal compoundfilm between the gate electrode portion GE and the semiconductorsubstrate 1100 (p well PW). The insulating film has a high dielectricconstant film having a dielectric constant higher than that of a siliconnitride film. As shown in FIG. 116, the peripheral transistor has, asthe insulating film, a silicon oxide film 1113 and a high-k insulatingfilm (high dielectric constant film) 1114. The high-k insulating film1114 and the gate electrode portion GE have therebetween a titaniumnitride film 1115 as the metal compound film.

The gate electrode portion GE has, on the sidewall portion thereof, asidewall film SW made of an insulating film. The source/drain region SDis comprised of an n^(÷) type semiconductor region 1119 b and an n⁻ typesemiconductor region 1119 a. The n⁻ type semiconductor region 1119 a isformed in self alignment with the sidewall of the gate electrode portionGE. The n⁺ type semiconductor region 1119 b is formed in self alignmentwith the side surface of the sidewall film SW and has a junction depthand an impurity concentration greater than those of the n⁻ typesemiconductor region 1119 a. This source/drain region SD (n⁺ typesemiconductor region 1119 b) has thereover a metal silicide film SIL.

The peripheral circuit region PA has therein a silicon oxide film 1121as an interlayer insulating film and this silicon oxide film 1121 hasthereon a silicon oxide film 1124 as an interlayer insulating film.

In such a peripheral transistor formation region, the gate electrodeportion GE may be formed, for example, by patterning without forming thesilicon nitride film 117 in the step shown in FIGS. 36 to 40 of FirstEmbodiment. Then, as in the memory gate electrode portion MG and thecontrol gate electrode portion CG, a metal silicide film SIL is formedover the gate electrode portion GE made of a silicon film.

Thus, for example, some of a plurality of peripheral transistors may beconfigured so as to have a gate electrode portion GE made of a siliconfilm without using the high-k/metal configuration. It is also possibleto form the gate electrode portion GE of all the peripheral transistorsas a gate electrode portion GE made of a silicon film.

Twelfth Embodiment

In the semiconductor device of First Embodiment, the memory gateelectrode portion MG has a sidewall shape. In addition, the control gateelectrode portion CG may also have a sidewall shape.

The structure of the semiconductor device of the present embodiment willnext be described referring to drawings. [Description on Structure]

The semiconductor device of the present embodiment has a memory cell(memory transistor, control transistor) formed in a memory cell regionMA and a peripheral transistor formed in a peripheral circuit region PA.

FIG. 117 is a cross-sectional view showing the configuration of thememory cell of the semiconductor device of the present embodiment. Thesemiconductor device is similar to that of First Embodiment except thatit has a control gate electrode portion CG in sidewall shape.

As shown in FIG. 117, the memory cell of the present embodiment has acontrol gate electrode portion CG arranged over a semiconductorsubstrate 100 (p well PW) and a memory gate electrode portion MGarranged over the semiconductor substrate 100 (p well PW) and adjacentto the control gate electrode portion CG. For example, the control gateelectrode portion CG and the memory gate electrode portion MG are eachmade of a silicon film. This silicon oxide film has thereover a metalsilicide film SIL. Further, the control gate electrode portion CG andthe memory gate electrode portion MG each have a sidewall shape.

In forming such a memory cell, for example, the polysilicon film 116shown in FIG. 32 of First Embodiment may be removed by a predeterminedthickness from the surface thereof by anisotropic dry etching. By thisstep, the polysilicon film 116 can be left in sidewall shape (sidewallfilm shape). Then, as shown in FIG. 39, with the silicon nitride film117 as a mask, the polysilicon film 116 for substitution of a gateelectrode portion is formed in the peripheral circuit region PA. Stepssubsequent thereto are similar to those of First Embodiment.

Thus, both the memory gate electrode portion MG and the control gateelectrode portion CG may have a sidewall shape. This makes it possibleto scale down the memory gate electrode portion MG and the control gateelectrode portion CG.

Invention made by the present inventors has been described specificallybased on the embodiments thereof. It is needless to say that theinvention is not limited to or by the above-mentioned embodiments butcan be changed without departing from the scope of the invention.

[Supplement 1]

A semiconductor device having:

a semiconductor substrate;

a first gate electrode portion arranged over the semiconductorsubstrate;

a second gate electrode portion arranged over the semiconductorsubstrate so as to be adjacent to the first gate electrode portion;

a first insulating film formed between the first gate electrode portionand the semiconductor substrate;

a second insulating film formed between the second gate electrodeportion and the semiconductor substrate, between the first gateelectrode portion and the second gate electrode portion, and along aside surface of the second gate electrode portion on a side opposite tothe side of the first gate electrode portion, and having a chargeaccumulation portion in the second insulating film; and

a metal compound film arranged between the first gate electrode portionand the first insulating film,

the first insulating film having a high dielectric constant film havinga dielectric constant higher than that of a silicon nitride film.

[Supplement 2]

In the semiconductor device according to Supplement 1,

the semiconductor substrate has, in a first region thereof, a firstelement having the first gate electrode portion, the second gateelectrode portion, the first insulating film, and the second insulatingfilm,

the semiconductor substrate has, in a second region thereof, a secondelement having a third gate electrode portion arranged over the secondregion of the semiconductor substrate via a third insulating film and asource/drain region formed in the semiconductor substrate on both sidesof the third gate electrode portion,

the third insulating film has the high dielectric constant film, and

the third gate electrode portion has a metal film or a metal compoundfilm.

[Supplement 3]

A method of manufacturing a semiconductor device having the steps of:

(a) forming a first conductive film over a semiconductor substrate via afirst insulating film;

(b) etching the first insulating film and the first conductive film toform a first recess in a first region of the semiconductor substrate;

(c) successively forming a second insulating film and a secondconductive film over the first conductive film and the first recess;

(d) removing the second insulating film and the second conductive filmuntil exposure of the first conductive film; and

(e) etching the first insulating film and the first conductive film toleave, via the first insulating film, the first conductive film in asecond region adjacent to the first region.

[Supplement 4]

In the method of manufacturing a semiconductor device according toSupplement 3,

the step (e) is a step of leaving the first conductive film also in athird region via the first insulating film.

[Supplement 5]

In the method of manufacturing a semiconductor device according toSupplement 4,

the step (e) is followed by the steps of:

(f) forming a third insulating film over the first conductive film;

(g) removing the third insulating film until exposure of the firstconductive film;

(h) removing the first conductive film to form a second recess; and

(i) forming a metal film or a metal compound film in the second recess.

What is claimed is:
 1. A semiconductor device comprising: asemiconductor substrate; a first gate electrode portion arranged overthe semiconductor substrate; a second gate electrode portion arrangedover the semiconductor substrate so as to be adjacent to the first gateelectrode portion; a first insulating film formed between the first gateelectrode portion and the semiconductor substrate; a second insulatingfilm formed between the second gate electrode portion and thesemiconductor substrate and between the first gate electrode portion andthe second gate electrode portion and having a charge accumulationportion in the second insulating film; and a metal compound filmarranged between the first gate electrode portion and the firstinsulating film, wherein the first insulating film is formed between thefirst gate electrode portion and the semiconductor substrate and betweenthe first gate electrode portion and the second gate electrode portionand having a dielectric constant higher than that of a silicon nitridefilm.
 2. The semiconductor device according to claim 1, wherein thesecond gate electrode portion lies in sidewall shape on one side of thefirst gate electrode portion via the first insulating film.
 3. Thesemiconductor device according to claim 1, wherein the metal compoundfilm lies between the first gate electrode portion and the semiconductorsubstrate and between the first gate electrode portion and the secondgate electrode portion.
 4. The semiconductor device according to claim1, wherein the first gate electrode portion has a silicon film.
 5. Thesemiconductor device according to claim 1, wherein the first gateelectrode portion has a metal film or a metal compound film.
 6. Thesemiconductor device according to claim 1, wherein the second gateelectrode portion has a silicon film.
 7. The semiconductor deviceaccording to claim 1, wherein the second gate electrode portion has ametal film or a metal compound film.
 8. The semiconductor deviceaccording to claim 1, wherein the semiconductor substrate has, in afirst region thereof, a first element having the first gate electrodeportion, the second gate electrode portion, the first insulating film,and the second insulating film, wherein the semiconductor substrate has,in a second region thereof, a second element having a third gateelectrode portion arranged over the semiconductor substrate via a thirdinsulating film and a source/drain region formed in the semiconductorsubstrate on both sides of the third gate electrode portion, wherein thethird insulating film has the high dielectric constant film, and whereinthe third gate electrode portion has a metal compound or a metalcompound film.
 9. A semiconductor device comprising: a semiconductorsubstrate; a first gate electrode portion arranged over thesemiconductor substrate; a second gate electrode portion arranged overthe semiconductor substrate so as to be adjacent to the first gateelectrode portion; a first insulating film formed between the first gateelectrode portion and the semiconductor substrate and having a chargeaccumulation portion in the first insulating film; a second insulatingfilm formed between the second gate electrode portion and thesemiconductor substrate and between the first gate electrode portion andthe second gate electrode portion and having a charge accumulationportion; and a metal compound film arranged between the second gateelectrode portion and the second insulating film, wherein the secondinsulating film is formed between the second gate electrode portion andthe semiconductor substrate and between the first gate electrode portionand the second gate electrode portion and having a dielectric constanthigher than that of a silicon nitride film.
 10. The semiconductor deviceaccording to claim 9, wherein the second gate electrode portion lies insidewall shape on one side of the first gate electrode portion via thesecond insulating film.
 11. The semiconductor device according to claim9, wherein the metal compound film lies between the second gateelectrode portion and the semiconductor substrate and between the firstgate electrode portion and the second gate electrode portion.
 12. Thesemiconductor device according to claim 9, wherein the second gateelectrode portion has a metal film or a metal compound film.
 13. Thesemiconductor device according to claim 9, wherein the first gateelectrode portion has a silicon film.
 14. The semiconductor deviceaccording to claim 9, wherein the first gate electrode portion has ametal film or a metal compound film.
 15. The semiconductor deviceaccording to claim 9, wherein the semiconductor substrate has, in afirst region thereof, a first element having the first gate electrodeportion, the second gate electrode portion, the first insulating film,and the second insulating film, wherein the semiconductor substrate has,in a second region thereof, a second element having a third gateelectrode portion arranged over the second region of the semiconductorsubstrate via a third insulating film and a source/drain region formedin the semiconductor substrate on both sides of the third gate electrodeportion, wherein the third insulating film has the high dielectricconstant film, and wherein the third gate electrode portion has a metalcompound or a metal compound film.
 16. A method of manufacturing asemiconductor device, comprising the steps of: (a) forming a firstconductive film in a first region of a semiconductor substrate via afirst insulating film having therein a charge accumulation portion; (b)successively forming a second insulating film and a second conductivefilm over the semiconductor substrate, over the first conductive filmand over the side surface thereof; (c) etching the second insulatingfilm and the second conductive film to leave, via the second insulatingfilm, the second conductive film in a second region adjacent to thefirst region; and (d) forming a third insulating film over thesemiconductor substrate and the second conductive film, wherein thesecond insulating film has a high dielectric constant film having adielectric constant higher than that of a silicon nitride film.
 17. Themethod of manufacturing a semiconductor device according to claim 16,wherein the step (c) is a step of leaving the second conductive filmalso in a third region via the second insulating film.
 18. The method ofmanufacturing a semiconductor device according to claim 17, comprising,after the step (d), the steps of: (e) removing the third insulating filmuntil exposure of the second conductive film; (f) removing the secondconductive film in the third region to form a recess; and (g) forming ametal film or a metal compound film in the recess.
 19. The method ofmanufacturing a semiconductor device according to claim 16, wherein thefirst conductive film in the step (a) lies in sidewall shape on thesidewall of a first film via the first insulating film.
 20. The methodof manufacturing a semiconductor device according to claim 16, whereinthe step (c) is a step of etching the second conductive film into asidewall shape.